FORCEFIELD BACK PROTECTOR PRO L2K EVO (SIZE MEDIUM) Kevlar thread construction for 5 times the tensile strength of steel. NitrexEvo triangular shock absorbing material. Repeat Performance Technology designed to no loss of protection after multiple impacts. Size Medium: Torso Length 16 3/4"  18 1/4" inches (generally for riders 5'9 - 6 feet tall)