If you assemble melamine cabinets or work with particle board or Medium Density Fiberboard (MDF), these unique fasteners have been specially designed to make your life easier. The large shoulder beneath the head locks the shank in position to minimize the possibility of board failure. An extra-long stem on the specially designed screw caps fits a hole in the drive recess, preventing most accidental removal. Screws require a pilot hole through both pieces of material. The 7x50 screws are recommended for use with 3/4" materials. 5 x 40mm screws require a 5mm pilot hole and are used with 1/2" material.