LWA20-48PO NB Low Shaft Support Rail:NB Linear Systems 48" Inch (1219mm) Length 1 1/4" inch Diameter Shaft LWA20-48PO NB Shaft Support Rail, 1 1/4" Diameter x 48" inch Long Shaft, the shaft is made of aluminum alloy, These support rails support shafts from below to avoid shaft deflection for long-stroke/high load application.