Air Lift Fittings 21170 Air Lift Company has developed dependable air spring suspension products since our inception in 1949. All our efforts are spent ensuring your safety and comfort by designing, engineering and manufacturing the highest quality suspension products. Pipe Plugs- 1/4" NPT countersunk hex Air Lift, Pipe Plugs-1/4" NPT Countersunk hex Air Lift Pipe Plugs- 1/4in Npt (Countersunk)