Thimble An insertion into a loop of fiber rope to protect the rope. Mostly the thimble is closed by splicing of the rope. Produced in cast iron or stamped and bent plate for the protection of fibre ropes and hawsers in a connection point of a mooring line. Primarily four types of thimbles are used: K3, K2A, K2B and tubular thimbles. The thimbles are supplied with a product certificate with chemical properties.