SPERZEL 3+3 Locking Machine Heads - Plus they improve tonal response. 2+3 models feature set of six high quality locking machine heads in a Chrome, Satin Chrome, Gold plate or Black plate finish for LP, PRS and similar guitars. Direct replacements for existing machine heads. Stay in tune without locking nuts by using hassle-free locking tuners. NEW - We now stock plain chrome Sperzel machine heads.