Sigma 17-50mm f/2.8 EX DC OS HSM FLD Large Aperture Standard Zoom Lens for Pentax Digital DSLR Camera<div style="text-align: left;"><strong>[Product Information]</strong><ul><li id="replacementPartsFitmentBullet" class="aok-hidden" data-doesntfitmessage="We're not sure this item fits your " data-fitsmessage="This fits your "><span class="a-list-item"><span id="replacementPartsFitmentBulletInner"><a href="#" class="a-link-normal hsx-rpp-fitment-focus">Enter your model number</a>to make sure this fits.</span></span></li><li><span class="a-list-item"> For use with smaller chip APS-c or 4/3 digital cameras only </span></li><li><span class="a-list-item"> Offers Sigma's OS System (Optical Stabilization) allowing handheld photography even in low-light situation </span></li><li><span class="a-list-item"> HSM (Hyper-Sonic Motor) ensures a quiet &amp; high-speed auto focus </span></li><li><span class="a-list-item"> FLD glass elements with performance equal to fluorite glass for compensate for color aberration </span></li><li><span class="a-list-item"> Ultra compact with overall length of just 3.6" </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/51%2BfdYEP5NL.jpg" noproxy>