Travis Haley is always all about speed and economy of movement. Since the famous Magpul video, he has expanded from being just a high-speed trainer into a low-drag innovator (I admit it, I own and regularly use an Incog holster).
His latest release is a rather nifty piece of plastic to assist with ammunition retention and management. It is (as expected), designed to work with his own design chest carrier, but seems that it would work in many systems out there.
Video below on the “MP2”.