This is a vibrato tailpiece developed by Paul Bigsby. Bigsby tailpieces were options on many Gibson guitars, while quite a few Gretsch guitars (the Country Gentleman, Nashville, and Tennessean to name but a few) came (and still come) with Bigsby tailpieces as standard equipment. The design is quite basic, with the strings extending across the bridge, and attached to the Bigsby. A bar or handle is used to bend the pitch of a note or entire chord up or down. A heavy-duty spring inserted under the handle helps return the strings to proper pitch.