Certain game kits like Weird Al’s Museum of Natural Hilarity and Heist were designed with shots only accessible with flippers on the Side-Target Flipper Assemblies.
All new P3s come with both left and right assemblies installed. Existing P3 owners might need to replace one or both of the non-flipper side-target assemblies in their machines.
Weird Al’s Museum of Natural Hilarity needs both a left and right side-target flipper assembly.
Heist needs only a right side-target flipper assembly.