This is a Tremulator from Demeter Amplification. About 10 years ago, I heard that Eric Clapton was using one, so I searched for a used one and bought it. It has a natural, pleasant tremolo sound. The power adapter is a mini-pin jack type, so I'll include it. Since it's a used item, please understand that it's sold as-is, with no returns or refunds. Please note that I will not be accepting any price negotiations. The following is text from a musical instrument store's website: The world's most well-known, classic vintage tremolo sound! Made for Ry Cooder, and also used by E. Clapton and Radiohead. The TRM-1 Tremulator, a super-classic tremolo effect pedal from DEMETER, was developed in 1982 at the request of RY COODER, the roots music explorer and brilliant guitarist. James Demeter completed the Tremulator, modeling its sound after RY COODER's vintage Fender Twin amp. Since then, the TRM-1 has been loved by many professional musicians, and Guitar Player Magazine in the US selected the TRM-1 as one of the "50 Coolest Effects Pedals of All Time."