STURDY METAL FRAME : This bunk bed made of strong steel construction with black powder coat finish; Weight limit of Lower bunk: 500 lb, Weight limit of Upper bunk: 300 lb. 14.5” SAFETY RAIL : This bunk bed twin with Extra High guard rail going around the top bunk to provides maximum safety so that you don’t have to worry about your little one over falling or getting trapped between the wall and bed. SOLID SQUARE FRAME : The square are more durable&Solid than the round in structure. Don't worry about if the frame will be broken, the maximum bearing capacity can reach 800 lbs! COMPATIBLE : Recommended Mattress thickness for Lower bed is 5" to 10" and Upper bed is 5" to 8". SAFETY : This bunkbed is approved by OSHA safety for kids camps , sleepovers and getaways. Weight of Bunk Bed : 30"= 99lbs , 33"=103lbs , 39"=125lbs.