From the product description, check product page for current description, price and availability:

• ➤ EASY INSTALLATION – The workbench casters include 4 workbench caster assemblies with assembly hardware, all the necessary mounting hardware, full instructions and an installation template for quick and easy mounting of the workbench casters to a standard flat base surface.
• ➤ SIMPLE OPERATION – This 4 casters work by simply pushing down on the pedals to raise your workbench off the floor. Once elevated you can move your bench, table or machine as desired, then lift up on the pedals to disengage and your workbench, table, cabinet, stand or machine sits firmly on the floor at its original working height.
• ➤ IMPROVED VERSION – The workbench caster kit uses thicker steel, stronger screws, three holes on the top and the bottom of the plate, better wheels and bearings. Add rubber sleeve to protect contact part between human body and the caster, new design which is different from other Retractable Casters
• ➤ DURABLE CONSTRUCTION – The heavy duty wheel casters are constructed with durable solid steel and urethane wheels, which can smoothly move 360 degree. The wear-resistant urethane wheels is more steadier for heavy duty benches. Suitable for extensive daily use like workbe.
• ➤ STRONG FOOT PEDAL – Each lift pedal is ribbed and textured to provide extra grip when foot pressure is applied. The 2-1/2” urethane casters are rated for 165 lbs of capacity, which means all four together give you a total weight capacity of 660 lbs. The casters will work on workbenches, stands, tables, cabinets and lightweight machinery with flat bases.