Up for sale is a barely used Problem Solvers Zinger XD Driver Single Speed Kit. This kid is a brilliant solution that allows you to run a single speed set up on your SRAM XD driver. It comes with everything needed, including an 18 and 20 tooth cog to dial in your preferred gearing. I used the 20 tooth cog for a total of four rides, and the 18 tooth cog is brand new, and not used. When purchased, I paid $75 for the kit, and it's practically in new condition, so I am asking a very fair $50 Plus shipping depending on location. Feel free to email/message me with any questions. Thanks!