Chain Stopper Diagram Chain Stopper for chain 6mm – 8mm / 1/4″ – 5/16″ Works with your anchor rollers to take the tension off the windlass by locking the chain. Handles 6 – 8 mm (1/4 – 5/16″) chain. Included a convenient foot tab for safe and easy operation. Mounted with 4 screw holes to increase breaking strength. Made in 316L mirror polished stainless steel.