U.S type Clevis Slip Hook Surface: galvanized or self -colored, plastic spraying Size: from 1/4" to 3/4" US type clevis slip hookA331 Hook A-331 Forged Alloy Steel. H-331 Forged Carbon Steel.A331 hookClevis Slip HooksH-331 Forged Carbon Steel. A-331 Forged Alloy Steel.Quenched & Tempered.Ultimate Load is 4 times the Working Load Limit.