The Craft-Lock® Series, which is constructed from recycled railroad steel, is designed for strength and endurance. The Craft-Lock has several important features: the wedge-lock leg makes the frame stronger as more weight is applied, the recessed legs allow for additional foot clearance and finally, the 1-3/4" high-carbon ribbed steel side rails provide maximum support for the mattress and box spring. No nuts and bolts mean no tools are needed for assembly.