A1 – Major diameter of thread.
A2 – Thread pitch
B1 – Outside diameter of locating lip
B2 – Length of locating lip
C1 – Flange height
D – Outside square dimensions of flange.
E – Outside diameter of bearing lip.
F1 – Mounting hole size.
F2 – Diameter on which the mounting holes are located. For flanges with even number holes, this is the distance between two opposing holes.