APEM Seal Caps for Toggle/Pushbutton Switches – Full and Half – APEM U133, The APEM Seal Cap U1331 Full with Knurled Nut Nickel-Coated, Black is an excellent solution for preventing dust, sand and water from getting into switches, while in cold weather, it also prevents ice from blocking lever action. Suitable for bushing APEM Series 5000 and 11000 switches. APEM U1331 Seal Cap Full with Knurled Nut Nickel-coated Black