Description The RJ-45 Rolling Jack is a scissor-style rolling bridge jack designed to be mounted in a four-post lifts jack rails. Manual pump operation requires no air making for a clean, uncluttered work environment for the professional shop and the car enthusiast. The scissor-style jack allows for level, wheels-free lifting to expand your four-post lifts capabilities. Features Low profile design 3 safety lock positions Powder coat finish Smooth sliding operation Spring-loaded rollers for positive jack rail contact Hand pump no air needed 4,500 lbs capacity allows passenger car and many heavy duty pickup trucks 1-1/2and 5 extension included (set of two each) Adjustable width fits most lifts Specifications Lift Model RJ-45 Max Capacity 4,500 lbs. Lift Height 3.75" 11.00" Lift Height 1 1/2" Extension 5.25" 12.50" Lift Height 5" Extension 8.75" 16.00" Arm Extension 34.25" 57.48" Base Adjustability 33.90" 49.60" Pad Height Above Runway 3.75" Weight 363 lbs.