Aluminum Tailpiece with mounting studs & anchors Made in the USA - not a Genuine Gibson part Lightweight vintage design - weight is about 1.2 oz. Plated aluminum alloy Includes plated brass studs(SAE 5/16 - 24) and zinc plated steel bushings - 1/2" (13mm) diameter Tailpiece ear thickness is .290"(7.4mm)The aluminum tailpieces weight 1/4 that of the zinc and produce a much different sound. They transfer vibrations differently,resulting in a woodier, more airy vintage tone -richer, rounder mids but with more upper harmonics as well. Back in the '50s, Gibson used aluminum for their stop bar tailpieces. For whatever reason, they switched to zinc, which is still used today on all but the historic line.

The aluminum tailpieces weight 1/4 that of the zinc and produce a much different sound. They transfer vibrations differently,  resulting in a woodier, more airy vintage tone -  richer, rounder mids but with more upper harmonics as well. Back in the '50s, Gibson® used aluminum for their stop bar tailpieces. For whatever reason, they switched to zinc, which is still used today on all but the historic line.