All SHUR-LOC hooks have the following features: Forged Alloy Steel - Quenched and Tempered. Recessed trigger design is flush with the hook body, protecting the trigger from potential damage. Easy to operate with enlarged thumb access. Positive Lock Latch is Self-Locking when hook is loaded. The SHUR-LOC hook, if properly installed and locked, can be used for personnel lifting applications and meets the intent of OSHA Rule 1926.1431(g)(1)(i)(A) and 1926.1501(g)(4)(iv)(B). Contact Engineered solutions for additional threading or Split Nut options to 1-800-777-1555. Eye Style incorporates these added features: Individually Proof Tested to 2-1/2 times the Chain Working Load Limit with certification. S-1316 meets the performance requirements of EN1677-3. 25% stronger than Grade 80. Suitable for use with Grade 100 and Grade 80 chain. Designed with Engineered Flat to connect to S-1325 chain coupler.