The LensCoat TravelCoat Cover for Sigma 500 f/ 4.5 Lens (Realtree Max4) is a 3mm thick shock-absorbing closed-cell neoprene lens cover. It is designed to fully protect the lens when not in use, without the need for a more comprehensive lens case. It allows more valuable room for packing and storage. The cover simply slides over the lens and closes with a secure touch fastener.