This is the 4-40 x 1 socket head bolt & blind nut set from Du-Bro.
Includes: Four each of bolts, flat washers, lock washers, blind nuts and one allen wrench
Thread Size: 4-40
Allen Wrench Size: 3/32
Screw/Bolt Length: 1
Inner Diameter (Flat Washers): 1/8”
Inner Diameter (Lock Washers): 1/8”