Hoffman VHDSPOST, Vhds Motion Arm Post Adptr, 5.00X4.00X4.00, SS Type 304Order separately when installing the SYSPEND¢ VHDS-Motion Arm to a 3.5-in. OD tube.Features:Type 304 stainless steelIncludes hardware to mount the adapter to the arm and setscrews for mounting to a tube