Yost 4" Machinist Vise with 360 Degree Swivel Base conforms to Fed. Spec. GGG-V-410B Type VI Class 2, and includes the following features: 65,000 PSI Tensile Ductile Iron Body Parts, Interlocking Swivel Base With 360 Degree Motion, 2 Lockdowns, No Pinch Main Screw Handle, Replaceable Hardened Steel Serrated Jaws, and Continuous Rolled Thread on Main Screw.