@Rich52 great question! Yes, the REI Co-op Kingdom Mud Room will be compatible with REI Kingdom 4, 6, and 8 tents, so long as you have a 2019 model year or newer. Because the Kingdom tents are all the same height (75) and width (100) and vary by length (100, 120, 150), the Mud Room will attach to the front of each model the same way. Hope this helps!