The TW-LS is an effects loop selector as well as an A/B Box intended to activate or deactivate an effects chain, allowing you to select, for example, the preamp section of your amp. With A/B mode, the TW-LS transforms into an A/B Box allowing you to connect one instrument and two amps or two instruments to one amp and choose between the two. The TW-LS also allows you to ''Mute'' the input and output by holding down the ''footswitch'' for a long time. The transparency of the selector has been particularly carefully designed so as not to degrade the signal and the harmonics passing through it.