A linear actuator is provided having a housing with a bore having at least first and second portions extending therethrough. The second portion has a polygonal geometry with substantially rounded corners having at least one planar bearing surface. A shaft is in sliding engagement with the first portion of the bore, and a piston member is operatively coupled to the shaft. The piston member has a mating geometry to the second portion of the bore, wherein the piston member is in sliding engagement with the second portion of the bore. An anti-rotation member is coupled to the piston member or shaft and has a generally D-shaped geometry with a planar anti-rotation bearing surface. Contact between the anti-rotation member and the housing is limited to a sliding engagement between the anti-rotation bearing surface and one of the at least one bearing surfaces based on an orientation of the anti-rotation member.