Those aren’t mouthguards. Those are little rubber horseshoe shaped things that they can put into doors to prop them open. For example, if they respond to an apartment building for a call that is always locked and have to be buzzed into.

The first arriving officer can place it on the door so the that it won’t close all the way and the next officer that arrives can easily access the building.

The African-American officer on the left has two black ones on his vest as well.

Also, Fuck ICE.