Whirlwind Selector A/B Box
Whirlwind Selector A/B box. Choose between one guitar to two amps, or two amps to one guitar. Also has a very useful “both” button…turns both on. It is used but working fine. There is velcro on the bottom.
It is without the power supply, and it takes a non-standard small pin adaptor for power (see the picture). You can also use a 9V battery.
From Whirlwind website:
The famous Whirlwind Selector is the only A/B A+B box that provides totally noiseless switching between channels. Send one guitar to two amps or use it the other way around to select between two guitars into one amp. Whichever way you use it, the Selector is the best channel-switching device money can buy.