The Diamond Effects Loop Jumper Cable is designed to be a jumper from your Effects Send to Effects Return jacks, activating your effect loop, and hence the E Return/Master Volume control without the need to plug anything into your loop. at 8" in length, this cable is just enough to jump the loop without having any unnecessary excess cable. Utilizing flat plug ends, this cable also keeps a low profile preventing accidental bumping when putting the amp in a head case or on/off the stage.