Metal Heavy Duty Center Support Rail System For Bed Frame (Adjustable Height). Prevent the middle sagging of your bed by strengthening it with this bed frame support rail system. Constructed from metal, this support system will hold heavier mattresses. The nylon base will help prevent the legs from scratching your hardwood floor. This support rail is designed to be used either on metal bed frame or wooden platform bed.• Twin, Full, Queen• Finish: Black; Silver Legs• Materials: Metal; Plastic Legs; Nylon Bottoms• Height Can Be Adjusted Between 7.5" through 14"HNote: To attach this support rail to a metal bed frame, the bed frame needs to have pre-drilled holes on the side rails, some bed frames may not have holes on the side rails. if there are no holes on the side rails of the frame, you will need to drill the holes so that the the support can be attached to the frame with bolts.