The Ikelite 6201.01 O-Ring Kit for 15 Push Buttons is a tool for seating the "O" rings in the push button shaft hole. Drop O-Ring in desired hole and push down with provided tool. The O-Ring should be flat in hole, if it looks to be tilted, push into hole again. After seating O-Ring drop in washer and spring. Make sure the black nylon washer is in place under the head of the pushbutton. Push the push button through, holding push button in until the e-clip has been installed on the proper notch.