Hex Head- Hex head screws enable for bigger torque. They are generally set up with a wrench and socket. Hex heads are common in screws and bolts. A Twin Screw is one that has two spirals of threads operating up the screw. They are frequently called Double Start out Screws https://typesoflanaiscreen74950.blogthisbiz.com/35548555/what-does-types-of-screwdriver-heads-mean