Up for sale is an used VPI Periphery Ring Clamp.  Highly recommended for VPI owners.

The Periphery Ring Clamp greatly improves the performance of VPI turntables by flattening the outer edges of LPs, increasing the cartridge’s tracking ability, removing resonance and aiding detail retrieval. A massive ring designed to sit just outside the lead-in groove, the PeripheryRing Clamp's weight flattens the record onto the platter, eliminating edge warps and more completely coupling the record to the platter.