It is a tube form composed of a fine weave glass reinforcement combined with a phenolic resin system. RT504F has properties similar to NEMA G-3 and MIL-I-24768/18, Type GPG materials (Although listed, there are no requirements). It is designed for high mechanical strength and temperature resistance in applications that require fine machining. RT504F is suitable for rings, collars, spacers, inserts, bushings, insulators, and tailstock.