Jacks worm,screw jacks,base screw jacks,base jacks 1.They are made from the steel and steel tube 2.Good Quality 3.OEM is off Jacks worm,screw jacks,base screw jacks,base jacksItem NoDescriptionWeight(kgs)No.451 3/8×245.5No.461 3/8×245.3No.471 7/8×367.9 Surface Finish: Galvanized, Powder Coated, Painted.HDG.ANY QUESTION PLEASE FEEL FREE TO CONTACT US screw jacks