External Length: 40/50/60 or 75mm. High Quality Nickel Plated M3.5 Socket Screws. Thread Size: M3.5mm. Single Full Thread with Slotted, Raised Head Socket, Switch and Front Plate Screws. These are the perfect screws to replace those in standard electrical sockets and are ideal for fixing a wide range of switches, sockets, wall plates and pattresses where different lengths may be needed.