People often like to retrofit their guitar effects with "true bypass" switches but this usually means wrecking the pedal case by drilling holes in it and stripping out the buffered section etc.
Personally I don't like doing this modification, I like there to be a buffer because there is always a degree of signal loss in pedal chains but this is here for those who do like to do it.
as it uses a mechanical relay (which can be found at Rapid Electronics or wherever - the one I used is the 12v version of this one ) it is exactly the same as a true bypass switch and adds nothing to the signal.
it is quite small so it can fit in some pedals (like a tubescreamer) or you could use it externally to maybe bypass a whole group of pedals (or just one of course)
it's worth mentioning that this has many other uses such as controlling high power relays with a little tact/push switch and so on
NB: if you find you're getting misfire clicks you can make the capacitor a higher value - that part acts as a crude debounce - the higher it is the more stable it becomes but the slower you can turn it on and off but I found 220n was fine for guitar bypassing
hope you like.
