DIN6796, Heavy Duty Belleville Washer for Bolt Size M12, OD: 29.0 mm (1.142") ID: 13.0 mm (0.512") Thickness: 3.0 mm (0.118"), Steel, Zinc Plated Flat Load 34100N (7,673 lb)(Pack of 10)
Belleville washer is a conically formed washer made from High Carbon Steel and hardened for spring like property. They are primarily used in Bolted joints to keep the bolt secure and prevent it from loosening in conditions like for vibration and thermal expansion