Enables Sigma 500 f/4 DG OS HSM Filter Use. The Sigma 500 f/4 DG OS HSM Sports (for Nikon and Canon) is a fantastic super telephoto prime, but its design prevents the use of traditional threaded filters. The Sigma WR Circular Polarizer RCP-11 Drop-In Filter gives users a circular polarizing option.

46mm WR Circular Polarizer Included. The integrated WR Circular Polarizer has a filter factor of 2 to 4x, meaning that your exposure time will increase by 1 to 2 stops. There’s a small wheel at the top of the filter holder that lets you rotate the polarizer to get the effect you want.