These are 2x3/8" 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: 3/8" Diameter: 2mm COMMENTS: This uses a 0.050" size allen wrench