The Rubber Guard is a synthetic rubber gasket that separates the FlatLink and the fairlead by a high durometer rubber material. The rubber guard feature was designed into the FlatLink from the beginning. Once installed, the Rubber Guard will not come loose and will protect both Hawse and Roller fairleads from scratching. We use EPDM instead of polyurethane because polyurethane products crack easily, plain and simple. EPDM is a synthetic rubber that has superior resistance to aging, cracking, UV, ozone and oxygen exposure. It is also extremely resilient and flexible. Although the cost to manufacture products from EPDM material is considerably higher than urethane, at Factor 55 believe that the choice to use EPDM has resulted in a longer lasting and superior engineered product. Installation instructions: Place the ProLink/FlatLink Rubber Guard barbs up on a flat surface. Moisten the barbs with soapy water or glass cleaner and place the ProLink/FlatLink on top of the Rubber Guard carefully aligning the barbs to the mating holes. Apply firm uniform pressure until all barbs have engaged into holes.