This is an image email to me by Yazan Hatahet. These are model representations of the various valves and crowns found on Rolex watches. From the left is the helium escape valve used on the Deep Sea and the Sea Dweller. The second valve is a screw in pusher from a Rolex Daytona. The third valve from the left is a traditional Rolex twinlock crown, and the last valve from left is a Rolex Triplock valve. The red sections in each model represent the rubber O-rings in each of the valves.