Opteka Auto Focus DG EX Macro Extension Tube Set for Pentax Q Series Mirrorless Cameras (Includes 10mm, 16mm, 21mm Tubes) Extension tubes are designed to enable a lens to focus closer than its normal set minimum focusing distance. Designed with all the circuitry and mechanical coupling to maintain auto focus and TTL auto exposure with Pentax Q series cameras and lenses Contains three tubes of different length, a 10mm, 16mm, and 21mm Glass-free; Lightweight 1 Year Opteka Warranty