This is a locking nut set removed from a 2005 Ibanez RG2550. It's an Ibanez TOPLOCK III, often used with the Edge tremolo system. This is the type of locking nut that is installed from the back of the neck. **String Retainer **Locking Nut Please refer to the description and photos, and we look forward to bids from those who understand the handling of guitars and parts in auctions.