The Volume Box lets you expand your amp"s range of usable volume & dial in much more "open" & "driven tube" tones at lower/more manageable volumes (without driving your neighbors crazy!). It adds another much more responsive audio taper volume control to the circuit of your amp by simply plugging into the effects loop, no mods required whatsoever and no danger of harming your amplifier. It solves the problem of an EXTREMELY touchy volume knob on your amp, you know what I mean: zero has no volume but 1 or 2 is already MUCH too loud. The Volume Box takes care of that with its nice smooth Audio Taper Control, DEFINITELY the most cost effective investment you can make for your amp, A great way to discover a whole new range of tones on your amplifier! Simply plug it into the effect loop on your amp (thats the preamp out and power amp in jacks, you need a series effects loop for this device, it does not go between amp and speaker) and turn the amp UP and then adjust the overall volume with the volume box...this allows you to get more of that wide open tube tone at nice safe levels, it really works great! Works on all amplifiers (tube and solid state even) with a standard (series) effects loop regardless of ohm load/power rating/impedance! A must have secret weapon every guitarist should have in their trick bag! Works great live, at home, in the studio, wherever! This box is made of super strong die cast aluminum, I use all quality components, very well made and absolutely WILL NOT HURT YOUR AMP! Yes you CAN still use your effects loop for other devices while using the Volume Box, just be sure to place the Volume Box last in the loop and everything will work just fine! Box is very simple to use, no batteries to change or anything like that, just plug and play!!! This is the best bang for the buck you will ever get for your amp! Cables not included, full moneyback satisfaction guarantee, thanks!!!