Sigma 17-50MM F2.8 EX DC OS HSM Zoom Lens for Canon with 32GB Accessory Bundle For use with smaller chip APS-c or 4/3 digital cameras only Offers Sigma's OS System (Optical Stabilization) allowing handheld photography even in low-light situation HSM (Hyper-Sonic Motor) ensures a quiet & high-speed auto focus FLD glass elements with performance equal to fluorite glass for compensate for color aberration Ultra compact with overall length of just 3.6"