Mains switch. For models Ferguson 151F, Ferguson 50855380, Ferguson A36F, Ferguson A36F, Ferguson A36R, Ferguson A36R, Ferguson A41F, Ferguson A51F, Ferguson A51F, Ferguson A51N, Ferguson A51N, Ferguson A59F, Ferguson A59F, Ferguson A59N, Ferguson A68N, Ferguson B51F, Ferguson B51F, Ferguson B51NX, Ferguson B51NX, Ferguson B78NT, Ferguson B78NT, Ferguson C51F, Ferguson C51N, Ferguson C51N, Ferguson ICC7, Ferguson RR5191N.