MLB has either had teams wear red, white and blue caps or camouflage caps for their nationals holidays in the past. This year, they will be wearing the above on Independence Day.
The design will use the same template and material as the batting practice caps. Crowns will be red with a navy brim or the reverse, with a navy crown and red brim. The underbrim appear to be all gray. The team logo will be white outlined in navy over a star with the flag design in the interior. (The Rockies cap in the image might be navy with a white outline.)
It appears that the American League could be all red crowns and the National League will all be navy crowns. At least that’s my assumption with this photo and a couple leaks in the past week.