LensCoatA(R) for the Sigma 50-100mm f1.8 DC HSM Art LensCoatA(R) Sigma 50-100mm f1.8 DC HSM Art lens cover offers your valuable equipment some protection from scrapes and bumps, preserving its resale value. It also helps break up the shape of your lens, making it less noticeable to wildlife. The LensCoatA(R) Sigma 50-100mm f1.8 DC HSM Art features a clear plastic windows over the auto focus controls and also the distance scale.