Foam Cushions are generally used with all types of surface mount pickups. Jazzmasters, jaguars, p90's and bass pickups can both benefit from having this underneath. They offer some height adjustability, but not as much as bolts and springs.
These cushions are provided with some double-sided tape to ensure that they stay in their place.
The bigger jbass sized will be delivered per piece, and the smaller pbass will be in a set of 2pcs.