LWA8-48PD NB Low Shaft Support Rail:NB Linear Systems 48" Inch (1219mm) Length 1/2" inch Diameter Shaft LWA8-48PD NB Shaft Support Rail, 1/2" 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.