APEM Seal Caps for Toggle/Pushbutton Switches – Full and Half – APEM U851, The APEM Seal Cap U851 Full with Hex 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 600H, 660, 1000, 1500 and 3600 switches. APEM U851 Seal Cap Full with Hex Nut Nickel-coated Black