Spring steel E-clip or C-clip fits shaft diameters of 3/8 in with groove diameter of 5/16 in.
Reference:
Bally P-2891-8
HDW-CRING38
Jersey Jack Pinball (JJP): 94-004011-12
Stern Pinball (SPI): 270-5012-00
REPLACES Williams (WMS): 20-8718-1 clip crimp style C clip
Williams 20-8712-37