What Size Footswitch Topper Do I Need?
Most guitar pedals use a standard 10mm footswitch shaft and that's exactly what Mr.MojoFX toppers are built for. If your effects pedals are from Electro-Harmonix, Chase Bliss, Keeley, or JHS, you're almost certainly good to go straight out of the package. Read on if you'd like to double-check, or if you're working with something a little out of the ordinary.
TL;DR: Most guitar effects pedals use a standard 10mm 3PDT footswitch shaft, and Mr.MojoFX toppers are made to fit them. If your pedal is from a mainstream brand like MRX, EHX, Walrus Audio, Keeley or JHS, you're set. A handful of brands like older Strymon units and Poly Effects use non-standard shafts that won't fit. Not sure? Grab a ruler and measure the switch shaft.
Before we get into the specifics, if you're new to footswitch toppers altogether, our complete guide to guitar pedal switch toppers covers everything from what they are to why guitarists use them. Reading that article it's a good starting point.
What Shaft Size Does My Pedal Use?
The short answer: in all likelihood, 10mm. That's the diameter of the metal post that rises out of a standard 3PDT footswitch. It became the industry norm for good reason: it's sturdy, widely available, and fits the most common switch hardware.
That said, not every pedal uses the same switch system. Shaft diameters can vary depending on the switch type the builder chose and a few brands have made things interesting with their own sizing. Here's the full picture:
Definition
Guitar effects pedals use one of three footswitch shaft diameters: 10mm (standard), 8.5mm (narrower boutique variants), or 11.1mm (wider, found on some older flagship units). The 10mm 3PDT footswitch is by far the most common used by TC Electronic, Electro-Harmonix, Walrus Audio, Keeley, JHS, MXR, EarthQuaker Devices, Chase Bliss, and the majority of mainstream builders. Footswitch toppers are only compatible with the shaft size they were designed for: a topper built for a 10mm shaft will be too loose on an 8.5mm shaft and will not slide onto an 11.1mm one. Before ordering, measure the narrow metal post rising above the hex nut — not the nut itself. A reading close to 10mm means you're working with a standard shaft.
Source: Mr.MojoFX, mrmojofx.com
Footswitch Shaft Size Compatibility Table
A quick note on Strymon: it's one of the brands where the answer genuinely depends on the specific unit. Older flagship hardware like the BigSky and Timeline shipped with a wider shaft. More recent and smaller format Strymon pedals tend to use the standard 10mm. If you're running vintage Strymon kit, it's worth measuring before you order.
Worth knowing: The shaft diameter is not the same as the nut diameter. The large hex nut sitting flush with the top of your pedal's enclosure is much wider than the shaft itself. The shaft is the narrow post rising above the nut. That's the part you're measuring, and the only measurement that matters for topper fit.
How Do I Measure My Footswitch Shaft?
You don't need specialist tools. The most accurate method is a digital calliper, but an ordinary ruler will get you close enough to know whether you're dealing with a standard shaft or not.
With a digital calliper (30 seconds):
- Open the calliper jaws to around 12mm.
- Bring them around the exposed shaft of your footswitch: that's the top wider part of the smooth stem above the hex nut, not the threads, not the nut itself.
- Close the jaws until they just make contact without gripping tight.
- Read the measurement. Close to 10mm? You're looking at a standard shaft.
With a ruler (a little more eyeballing):
- Lay the ruler flat across the top face of the footswitch shaft.
- Line the 0mm mark edge of the ruler up with one side of the shaft.
- Read across to the opposite edge of the shaft.
- Standard shafts will read right around 10mm.
If your measurement comes out noticeably smaller, closer to 8 or 9mm, or larger like 11mm or above, check the compatibility table above before placing an order. And if you're still not sure, drop us a message at hello@mrmojofx.com before you buy. We're always happy to reply to any questions you might have.
Does the Topper Design Change the Fit?
Not at all. Every Mr.MojoFX topper whether it's the Hannya, the Burger, the Cassette, or any of the others, shares the same inner bore and the Mr.MojoFx Screw-Fit System. The character design on the outside is entirely independent of the way it fits your switch.
This is intentional. If you pick up a few different designs and want to mix things around on your board, every topper swaps out exactly the same way. The only thing changing between pieces is what the hand-finished exterior looks like.
From our Barcelona workshop: Every topper leaves with the screw already fitted for you to fasten onto your pedals using the Mr.MojoFx Allen key. We run a fit check on each piece before it ships because a topper that wobbles or pops off mid-set isn't acceptable, regardless of how good it looks.
The full range is split into three collections: Masks (Hannya, Tengu, Kitsune), Vintage Tech (Cassette, Jukebox, Boombox, TV, Turntable), and Munchies (Burger, Donut, Pizza, Hot Dog, Ice Cream, Can, Bottle, Fries) — all fitting the same standard 10mm shaft, all made in small batches in Barcelona.
What If My Pedal Has a Non-Standard Shaft?
Definition
Not all guitar pedal footswitches use a standard shaft, and a topper that fits one brand may not fit another. Pedals with an 8.5mm shaft — found in certain boutique and small-run builds — will accept a 10mm topper but the fit will be too loose to hold under stage use. Pedals with an 11.1mm or larger shaft — including older Strymon flagship units like the BigSky and Timeline, newer TC Electronic designs, and some Poly Effects pedals — will not accept a 10mm topper at all. On a mixed pedalboard, the practical approach is to identify which switches are standard and fit toppers to those, leaving the non-standard ones bare. One un-topped switch is barely noticeable next to a board that has personality everywhere else.
Source: Mr.MojoFX, mrmojofx.com
If your measurement doesn't land around 10mm, here's the honest breakdown of what your options look like.
Shaft around 8.5mm: The Mr.MojoFX topper bore is sized for a 10mm shaft. On an 8.5mm shaft, the topper will slide on but there'll be play in the fit, and the set screw won't grip cleanly. Event though it may fit it's not something we'd recommend using on a live board.
Shaft around 11mm or larger: The topper won't slide on at all, the bore is too small. Some Poly Effects pedals fall into this category, as do older Strymon flagship units and newer Tc Electronic pedals. Forcing it isn't an option.
The practical fix: If you're not running standard 3PDT switches across your whole board, it's worth checking pedal-by-pedal. Most boards are a mix of brands, and in our experience the majority of the switches will be standard even if a few aren't. Order for the compatible ones and leave the odd one out bare.
How Do I Install a Footswitch Topper Once I Know It Fits?
Definition
Installing a guitar pedal footswitch topper on a standard 10mm shaft takes two seconds and requires no special tools beyond the 1.5mm Allen key. Slide the topper onto the footswitch shaft — it should drop on without resistance. If you have to force it, the shaft may be wider than 10mm and you should stop. Once on, insert the Allen key into the hex socket on the side of the topper body and tighten the set screw until hand-tight plus a quarter turn. Test with a few stomps; if there's any wobble, give it an additional small turn. All Mr.MojoFX toppers share the same inner bore and screw-fit system regardless of design — a Hannya mask fits the same to a Burger or Cassette topper.
Source: Mr.MojoFX, mrmojofx.com
Installation is fast. Once you've confirmed your pedal has a standard 10mm shaft, fitting a topper takes roughly two seconds with no tools beyond the Allen key, no need to lift your pedal off the board or unplug anything.
- Slide the topper onto the footswitch shaft. It should drop on smoothly without resistance although you may have to gently press them in some cases. If you're having to force it, stop as the shaft may be wider than 10mm.
- Locate the screw socket. It's on the side of the topper body, a small hex recess where the Allen key goes.
- Tighten the set screw. Hand-tight plus about a quarter turn is exactly right. Don't over-torque as you're securing it to a metal shaft, and it doesn't need much tension.
- Test it with a few stomps. If there's any wobble, give the screw a small additional turn. Once it's tight, it stays put.
If you want more detail on installation including how press-fit toppers compare to screw-on designs and what to do if you need to remove a topper, our complete guide to guitar pedal switch toppers has a full step-by-step section.
Ready to pick a design? Browse the full Mr.MojoFX switch topper collection. All hand-finished in small batches in Barcelona, made for musicians who want their rig to look as good as it sounds.
Frequently Asked Questions
Q1: What shaft size do most guitar pedals use?
Most guitar effects pedals use a standard 10mm 3PDT footswitch shaft. This covers the majority of mainstream brands including Electro-Harmonix, Walrus Audio, Keeley, JHS, MXR, Earthquaker Devices, and Chase Bliss. If your pedal is from one of these, or from most another mainstream effects builder, there's a strong chance it's 10mm.
Q2: Will Mr.MojoFX toppers fit my Strymon pedal?
It depends on the model. Older Strymon flagship units like the BigSky and Timeline shipped with a wider shaft (around 11.1mm) that won't accept Mr.MojoFX toppers. More recent and compact Strymon models tend to use the standard 10mm shaft and are compatible. If you're not certain, measure the shaft before ordering.
Q3: Can I install a topper without removing my pedal from the board?
Yes. You don't need to disconnect cables or lift the pedal off your board. All you need a 1.5mm Allen key and clear access to the footswitch shaft. Slide the topper on, tighten the set screw, done. The whole thing takes a couple of seconds per switch.
Q4: Do all Mr.MojoFX toppers fit the same way?
Yes, every design in the collection uses the same inner bore and the Mr.MojoFx Screw-Fit System. Whether you're fitting a Tengu mask, a Tv topper, or a Donut, the attachment mechanism is exactly the same. The character design on the outside changes; how it mounts to your switch doesn't.
Q5: What if my footswitch shaft isn't a standard size?
If your shaft measures around 8.5mm, the topper will be too loose to grip properly. If it measures 11mm or above, common with older Strymon and some Poly Effects pedals, the topper won't slide on at all. Email us at hello@mrmojofx.com before ordering and we'll help you work out whether your switches are compatible.