Chris is correct, my first few troops were a learning experience to say the least. Modifications and changes were required after the first few troops to get the armor fitting as it should. Once i got a pack there were more adjustments with my TD.. Today the longest ive been in armor for 7 hours with 2 drink breaks. (Full gear/w pack and T21) Hydration is key, once your in armor you will not be going to the bathroom and sweating the whole time. Ive moved over to UA 20% compression heatgear to keep the temp low wile in armor and it extends my troop time significantly.