Size 3 45mm Plain Bearing Pulley Block Double with SwivelThe size 3 Barton plain bearing blocks have a 45mm (1 3/4" sheave size 3 block range that incorporates modern design with stainless steel frames and the latest advanced materials, using 30% fiberglass filled nylon and Acetal sheaves to maximize their strength while keeping weight to a minimum. Suitable for use as mainsheet, vangs, lead blocks, or wherever a powerful and compact purchase system is required on dinghies, dayboats, and lightweight cruisers.Suitable for up to 10mm (3/8") rope. Quick Guide (pdf)