This bracket colors the building inserts in the center of the playfield with a progressive gradient, as well as the biplane arrow inserts and the "Naegele Oil" insert at the top of the building, taking them from a field of plain yellow and white to an easy indicator of your progress in the game.
This massive 15 insert bracket was a really hard one to get right. The goal was to have a progression of blues up the building lights, but since the plastic inserts were hard yellow from the factory, that was not possible. So a progression of yellow to orange that was compatible with the stock yellow inserts and still informs your progression was done instead.
Because the yellow to orange gradient progression was used on the building, it couldn't be used on the arrows to match the art because THEY are supposed to stand out also, not match the building lights. So for the biplane arrows a progression of blues was used to symbolize elevation in the atmosphere.
For the ATTACK insert, the initial thought was to make it red or leave it white, but after trying both, neither looked good, so green for "GO" turned out to be the best choice. Finally, the Naegele Oil insert was kept in the blues and purples to have a relationship with the art, which has a dark blue background on that area of the building for the backglass.
The bracket simply slides over the standoff posts on the light board under the playfield and is a 5 minute install.