HHIP 3901-0006 Ultra Quality 58 pieces clamping kit for 5/8" t slot and stud size 1/2-13. It is made of IC45e steel for more strength. All parts are case hardened or heat treated to HRC30-40. Manufactured at a world class factory that also produces high quality U. S. brands. Kit contains: 24 Studs: 4 of each 3", 4" 5", 6", 7" 8" long; 4 Coupling units; 6 Flange nuts; 6 forged steel step clamps 2 each based on stud sets; 6 T-nuts; 12 steel step blocks; 1 Wall rack.