The black rubber bumpers snap onto the end/edges of the green. Locate the internal retention teeth, and orient the teeth to snap onto the end/edge of the putting green. There are two openings on the bumper. The second opening points upward when installed properly. When installed properly, the bumper will have a raised lip that stops a golf ball from rolling off the green. In high traffic areas, bumpers can be taped on from the under-side of the green using duct tape. This will help with bumpers and trim being kicked off if necessary.