... .S. square tube; both sides are made of S.S. plate with sliding door (steel wire mesh)easy for ventilation ... wire, flat and smooth.The front is made of steel wire mesh, with accessories such as sliding door, extrusion drawplate, climbingpole ... , thus giving them proper activities.4'' wear-resistant caster with polyurethane brake, not scratching the ground; stainless steel monkey cage(double layers)