I bought these to modify a Peavy footswitch and they aren't going to be a direct drop in to fit. My fault for not looking at the footswitch housing more carefully before ordering but the shaft of each switch is encased in the molded footswitch housing so that the entire length of the switch shaft is encased in plastic. This means that there is no extra height available on the switch shaft to mount the ring LED. I guess it could be accomplished if I modify the length of the plastic encasement from the bottom of by about a 1/4" so the switch threads would protrude through the top farther which would then allow the LED ring and the switch nut to be placed, but that would risk cracking the entire casing so...
The LED all worked when tested with a 9V battery and would look really cool if I do mod the housing, so 5 stars for the product and quick shipping. I just wanted to make this review for any Peavy amp owners so they'd know what extra work needs to be done if they are thinking of modding the old style molded plastic footswitches. Of course there would also be the footswitch specific electrical voltage reduction needed to make it work and not blow out the LEDs and keep the switches being functional. These would work fine on thin metal footswitch housings.

Awesome product actually used it on a custom guitar build .

This thing is GREAT!
I have a boost pedal I love but is does not have a LED to indicate when the second level of boost is switched on.
The installation was simple (do use a step drill to enlarge the switch hole) with no need to calculate and install a resister -just hook up and go. It's bright enough to see in any situation but not so bright it blinds you!
Highly recommend!

I used this footswitch ring as a power indicator for a project amp. The ID will fit a standard 15/32" toggle switch. You can carefully pry out the led portion of the ring and change or remove the dropping resistor. I chose to short over it and use an external resistor. A 100ohm series resistor works well on a 6.3Vac filament supply, just don't forget to install an extra diode in reverse parallel across the ring's leads.

These are pretty cute. I haven't actually built my pedal with them yet but I connected them to power and tested them out. Functionally they're not really any better than a LED protruding through the top of the pedal but I think they'll add a little pizzazz to my project.