This is a cover for the naked coil that diverts the ball onto the crossbow lane when the feature is qualified. There are five color options, Gray, Gold, Black, Red, and Brown.
The cover slides onto the coil and is pressure-fit with the ramp hole sides, so it's very snug. It may be necessary to loosen the two screws on top holding the coil bracket to allow enough of a gap with the ramp hole to slide the cover onto the coil, and then re-tighten and align the bracket once the cover is on. If the ball hits the cover when it should be rolling past (and not diverting to the crossbow), loosen the two coil bracket screws on top and adjust it back slightly, then retighten.