Sigma TS-21 Tripod Collar for Select Telephoto Lenses

The Sigma TS-21 is a Tripod Collar Available for APO 135-400mm F4.5-5.6 DG, APO 170-500mm F5-6.3 DG, APO 70-200mm F2.8 Ex DG MACRO HSM, APO 70-200mm F2.8 Ex DG /HSM, APO 100-300mm F4 Ex DG /HSM, APO 120-300mm F2.8 Ex DG HSM, APO MACRO 150mm F2.8 Ex DG HSM, APO MACRO 180mm F3.5 Ex DG /HSM and APO 300mm F2.8 Ex DG /HSM.