Bolt-On Bed Rails Our WSP Bed Frames for Metal or Wood beds are made of high carbon remanufactured rail steel to provide extra strength and stability. This frame has 1.5″ side rails and 1.25″cross arms. Some models are provided with a 2″ center support that provides extra support to ensure a long life of your mattress and box spring.SM1001 1 1/2” x 1 1/2” High carbon rail steel side rails 1 1/4” x 1 1/4” High carbon rail steel cross arms Bolt-On and Hook-On Versions Hook-On versions with C-Clamps for width adjustment Keyslot Cross arms and Spring Clip Assembly on Bolt-On versions assure easy assembly and secure support Heavy-duty locking legs Item Description: