Got an email from IMR today, Murata (Sony) is now offering a VTC6a. A 40A, 4,100 mAh 21700 battery. That's news to me, but maybe not to others, and if so, my apologies. A 40A 21700 with 4,100 mAh capacity really puts a hit on dual 18650 mods unless you're really at very high wattage. I'll be watching for test results on this one to see if those claims are legit.