*Ronstan's rope sheaves leverage the self-lubricating properties of Acetal to deliver high strength, durability and excellent low friction properties for bearing applications. Moulded from a specifically modified ultra-violet resistant grade of material to ensure a long service life in the harsh conditions of a marine environment. UV resistant.1 15/16" x 19/32" (50mm x 15.6mm)Inside opening: 11/32" (8.1mm)Maximum rope: 9/16" (14mm)