The directional butting of the Energy SBS SB20 seatpost's 6066-aluminum shaft gives it thicker walls fore and aft for stiffness and thinner walls at the sides to cut weight. A forged and machined alloy head is bonded to the top of the shaft. - 3D forged and CNC machined AL6066 w/ alloy head - Directionally butted for low weight and additional strength - Chromoly hardware - Clamp Style: Standard Rails