SeaSure General Purpose Block [02.01CRD]General Purpose Block The 19mm carbon fiber sheave block range is designed for use with abrasive ropes for high load applications. The outer cage is manufactured from marine grade 316 Stainless Steel with a hollow stainless steel rivet through the center of a carbon fiber sheave. Features: The block features a plain bearing, which is suited to higher load use A typical use for this block is for control lines, halyards, outhauls, furling lines, etc.