Socket Screws 4 Pack 3.5mm x 75mm Powermaster 75Mm Socket Screws 4 Pack | 1521-06 The Powermaster Socket Screws - 3.5 x 75mm are used where up to 75mm is needed on the screw, for example if the socket is being placed in a deep cavity box where the 35mm screws provided would not suffice. The pack contains four screws and has hassle free, easy to open polyurethane packaging. They require standard installation tools and should only be installed by a competent, qualified person.