These ladders roll with ease, yet lock securely in place while in use. they are ideal for a wide variety of warehouse, stockroom, maintenance and shop floor applications. rugged square tube construction is 40% stronger than round tubing and welded sub assemblies for extra strength. 300lb capacity. Rigid 1" square tubing. 2-4 steps have spring loaded 3" casters which provide mobility while rubber-tipped legs add traction while in use. 5-16 steps have an Ezy-Lock that features 4" casters which are released putting ladder legs firmly on the floor when pressure is applied to bottom step. 16", 24", & 30" wide steps. Steps are 7" deep with a deeper 14" top step. Perforated or Grip Strut Tread for slip resistance footing. Meets OSHA standards.