The BLACK Hammer-Spacer HSP-T6 is a square tool made of steel that slides over the Oz-Hammer (OH-01) and keeps it centered on the inside of the Oz-Post sleeve when installing the T6-850 and T6-700. This Hammer Spacer is used in conjunction with the OH-01 Oz-Hammer. The OH-01 Oz-Hammer is 2” in diameter. The T6-850 and T6-700 are 5-1/2” inside diameter so we recommend using the HSP-T6 to keep the Oz-Hammer (OH-01) centered in the Oz-Post sleeve during installation.