This Zenith Lumbar Drop Piston contains 1 Drop Piston to repair broken bolts in a Older Style Zenith 320F, Zenith 440F, or Zenith 460F drop. This Zenith Lumbar Drop Piston is made for any zenith table with a 2 part roll finger style drop ( see Picture ). This piston is a Medium install job; basic mechanical knowledge is needed and is about a 30 minute job total to install.