The TonePros System II Bridge and Tailpiece components come as a package set, ready to install on your guitar. The package includes: 1. TonePros Patent Issued System II Pre-Notched Bridge with matching threaded adjustment posts. 2. TonePros Patent Issued System II Tailpiece with matching threaded adjustment studs. 3. Allen style adjustment tool for use with both bridge and tailpiece. The LPM04 includes the TonePros T3BP Bridge and T1ZS Tailpiece. These matched bridge and tailpiece are Standard thread and fit most USA guitars without modification.