w set screws

upper knob 19 wide x 13 high; internal diameter 4.85mm
lower knob 25 wide x 11 high; internal diameter 6.9mm

Top Knob - Inside diameter .192", 3/4" diameter, 1/2" tall.
Bottom Knob - Inside diameter .272", 1" diameter, 3/8" tall.

Concentric pots to fit - EP 4585-000 250K/500K; EP 4586-000 500K/500K