Manufactured by Bausch & Lomb Optical Company these are a set of screws made for Bubble Sextants. Made in August, 1949 these screws are 2.5mm long with a thread diameter of 1.75mm and a head diameter of 2.75mm. The Navy Stock# is R88-BL0-90045-11. The set comes in the original unopened Bausch & Lomb coin envelope. Antique military collectable!