The new Contractor Series HercuLoc Secure Bed Cover is more secure than a shell. Internal rotary slam latches lock the cover at each corner. The cover is counter-balanced on torsion springs and is easy to open. Either side or both sides can be opened at once. You have to pull the cover down against the torsion springs to close it. The truck can be driven with the cover raised. It is a very simple and robust design with all-steel construction and nylon bearings. There are no gas springs to fail. Thacker Manufacturing, Inc., Tucson AZ, 520-743-7639, www.herculoc.com.