Model Series: H-330Chain Size: 1/4 inch Material: Forged Carbon Steel (Quenched and Tempered) Working Load Limit (WLL): 2,600 lbs (1.3 tons) Design Factor: 4:1 safety factor (Minimum ultimate strength is 4 times the WLL) Chain Compatibility: Engineered to fit Grade 40 / Grade 4 Carbon steel chains (such as Crosby Spectrum 4®).