New Set of 4. Heavy Duty 6″ x 2″ Spring Suspension Tool Box Casters / 1,000 lbs. Weight capacity per caster / holes are 4″ x 4 1/2″ on center / Overall height 9 /. The hole measures 7/16 / diameter. Self leveling casters to help keep your tool box level on uneven surfaces / Roller bearing type / Hardware not included. / Blow Out Sale /.