Electro Harmonix Hum Debugger

This is effective at stopping the hum from a single pickup guitar. It has two settings 'Strong' and 'Normal'. For a Gibson Les Paul with P90's I find that the normal setting stops the hum without my noticing any distortion to the sound of the guitar though I don't tend to play a quiet sort of style so others might find different results. I'm not sure what else you'd use this for apart from removing that pickup hum - and it's not very versatile in that you have to use the included power supply as it requires 7'5voltAC at 200ma - which means you need another power-point. The unit itself is as most electro-Harmonix effects in a substantial metal box with a bypass button and a switch to select between the two modes on the top.

Very good hum blocker for single coils on my Fender Strat & Tele from LED lights etc. Through a Roland Blues Cube Stage, even at loud vol levels, (and this thing IS loud - like a driven tube amp). Really good result in noise removal.