Enhanced Power Buffer Spring. The design loads of the Blue spring are approximately 15% greater than the White spring for one of the considered Load Constants in the spring design. Refer to provided tuning procedure reference documents prior to calling for recommendations. We were encouraged to manufacture the Blue spring by Mike Pannone of CTT Solutions, who modified one of our Red springs and recommended that we offer a spring with the loads of the Blue spring to address the high performance demands of other specimen platforms. While contemporary internet forum lore leans towards the use of the Blue spring with an H2 or ST-T2 buffer for 14.5 - 16” ML carbines, nothing is set in stone due to the vast range of gas port values in the wild that have come into play since we first entered the arena.