per jack stabilization & performance capacity per jack capacity per jack bubble levels rv level plastic with easy to read yellow-green glass vial levels stick-on to rv surface with adhesive backing or permanently install with screws indicates side-to-side and or adhesive mount show when trailer or rv is level side-to-side and end-to-end rv level electronic levels 8"l x 8"w x 2h stabilization & performance see page 223 for details | catalog & internet only