So that is a trauma pack made by some buddies over at Frog Pro. If I am competing, or on the range and it is a live fire event I wear it. As an instructor or a RSO it is our responsibility to administer first aid rapidly if needed. Often times at ranges the first aid kit is 100s of yards away. By having it on my ankle I can be both mobile and always ready. I have enough junk around my waist if I am in full battle rattle. I wear suspenders already to distribute my load to my shoulders. I do not like hanging weight on my waist. Long story short it is just easier for me and more comfortable, after awhile you have no idea it is even on your leg. Plus I am just plain lazy so having it always with me saves all them steps fetching stop leak from the aid station!