ProTool 6-1/2" Velcro Backing Pad - Fits M16 and 5/8" Male Spindle - Polisher Buffer Multi-purpose backing pad plate that fits both metric (M16) and SAE (5/8" 11TPI) spindles Durable ABS base with poly pad to help protect finishes Strong Velcro hook-&-loop keeps accessory pads firmly in place without slippage 5/8" adapter adds extra inch of clearance - great for use with double-sided bonnets 6-1/2" diameter plate fits 6" and 7" foam pads, wool & cotton bonnets