These are all inserts that pull out of pouches, the others are on a quick detach Velcro system. The inserts work well when you need to save someone fast and want all your stuff spread out and well organized
That looks like the Chinook TMK IFAK. I think it is only removable from the insert and not the pouch itself. It is the elevator strap for when you put in supplies you pull on it and it raises your contents when you don't have the additional insert and think its sewn into the main pouch. The picture you showed is the additional insert you can buy for it. The elevator strap then doubles as a leash that attaches to the insert via hook and loop. At one point I was going to buy one of those but so expensive and I could develop my own kit for cheaper. I like the design of it though.