Pop Bumper Spring (small)
Ships from US and is sold by Pinball Life$0.70
This spring sits between the pop bumper base and the underside of the pop bumper skirt on almost all brands of pinball machines.
Williams/Bally #10-7, A-10430, and SP-200-177.
Stern/Sega/Data East #266-5048-00.
Jersey Jack Pinball #13-007003-00.