-A base plate with a diameter of 203 mm (7.99 in.), thickness of 15 mm (0.59 in.) with a bottom radius of 1 mm (0.039 in.).
-A feeler arm of high-speed steel comprising a flat bar, 12 mm wide (0.47 in.), 0.51 mm to 0.76 mm (0.02 in. to 0.03 in.) thick, with square-cut ends that is positioned over a radial axis of the base plate and attached to the base plate such that the feeler arm overhangs the edge of the base plate by 40 mm (1.57 in.).
-A level indicator attached to the base plate near the feeler arm, without touching, and such that it indicates level with minimum accuracy of 3.56 mm/0.3 m (0.14 in./ft) parallel to the feeler arm and does not overhang the edge of the base plate in a way that interferes with testing.
- A vertical column with handle and collar attached to the center of the base plate.
-Total mass of the apparatus shall be 5200 g (11.46 lb), including all components and fasteners.
-Mass of the base plate shall be not less than 70 % of the total mass.
-Vertical height of assembled apparatus shall not exceed 203.2 mm (8 in.) and the height of the collar shall not exceed 50.8 mm (2 in.) to minimize the bias to the base plate.