Phokus Research Group has been up to some crafty products for a while, one being their Sons Trauma Kit which offers an interesting alternative to traditional medical blow out kits. Rather than being a kit with a fancy pouch, the kit is shaped flat and slim sitting behind one's armor plate to make a great use of tactical space savings.
At the balance of perhaps not being the super fastest to deploy medical kit, The Sons Trauma kit can still be accessed in a quick manner, able be accessed by either hand, is almost unperceivable when worn, and saves space to allow more room on one's loadout for other important kit. This seems a fair balance as we still do need a medical kit for when lady luck skips out on day, however typically on duty folks are going to need to access other pouches a lot more often than medical IFAK pouches.
Although the Sons Trauma Kit can be placed into about any plate carrier, having one that has lower opening separate soft and hard armor external access should be a strong consideration. Usually the hard armor pocket has a pretty serious closure due to the intended carry weight while the soft armor pocket tends to have a lower key velcro closure. Due to this, one of the most preferred setups is to have the Sons kit in the soft armor pocket with the main pull tab sticking out through the opening allowing the easiest pull out access while being worn. An example of this would be seen on the First Spear AAC carrier, yet even on vests with separate soft armor pockets, having some other sort of retention is common. This can be seen easier on the Eclipse RBAV-AF which has the soft armor opening higher up rather than being at the bottom, which does make sense as the main purpose is to keep the soft armor in there even if the velcro seal gives out. For better or worse this causes enhanced retention on the Sons Trauma Kit, making it more difficult to extract one handed.
Like on any pouch, having 2 hands available makes things easier and faster to deploy the Sons Trauma Kit, but it being capable to be accessed by others, one's self, and with only one hand are all very important design features to be seen on any IFAK. Since the Sons sits under armor, which can be under even further heavy ammo and other gear, I found it a lot easier to release at least one side of the vest to provide more room and less tension to access. Although the pull tab is durable, if caught on something more durable, which pretty much describes any vest or carrier, the pull tab will break before the rest of the kit comes out. Thus focus should be on making a clean opening rather than muscling through a less desirable opening. Although deployment is still possible while sitting, it is easier while standing or laying down since easier to access the armor pockets.