These are 4x3/4" Button Head Sheet Metal Screws by Du-Bro. FEATURES: Zinc plated metal construction with clear chromate. Non-slip socket drive insert. The large head of the screw acts as a washer. A new design that"s great for mounting servos, cowls, landing gear, etc. INCLUDES: (8) Screws SPECS: Length: 3/4" Diameter: 4mm COMMENTS: This uses a 1/16" size allen wrench (GPMR8006) kr3/29/05