I ordered two of these Pro-Z-14 5200mah batteries in February when they were first release. Both were from Hong Kong/China shops. One just arrived today. That's probably the slowest shipping I've ever encountered, and I buy stuff from Hobbyking's intl warehouse First, this thing is tiny. Its dimensions are almost PRECISELY the same as my homemade 4400mah 3S2Ps, and it's way smaller than my Maddog 5400mah. It's so compact that I had to add a bit of tape to the top edge of the battery so my battery door latch would close. As an aside, the size makes sense. When the Vision was first announced, pre-release pictures came out showing a 4400mah 3S2P. DJI always claimed that the production model would be 5200mah, but nobody really believed it, because the 4400mah fit the production battery bay and cage already. But lo and behold, we got the smart battery as a 5200! In precisely the same size as the 4400 pre-release. So there's precedent on the identical size between these two capacities. Pro-Z-14 on the left, DJI 4400 middle, Maddog 5400 right View from above: It's also featherweight. I've made about 10 sets of 3S2Ps so far, and the DJIs are consistently 323-324g. This 5200mah comes in at 315g after I clipped off the HXT connector and replaced it with an XT60. It also feels well made, with cleanly aligned, straight-edged cells, unlike some of the Zippys and Turnigys I've opened up. But the big question is, how does it fly? Does a 10C 5200mah hold up? Does it compare to the P2's smart battery? I charged it up and took a single test flight with my Phantom. 1206g AUW, gimbal, gopro, 600mw vtx, iOSD mini, 9443 props, 5200mah battery. Slight wind, mostly easy flying and hovering--my usual AP-style battery test flight. Alarm 1 (10.6v) hit at: 14 minutes. Huh. I've been watching the voltage discharge on the iOSD, so I can see that the curve is extremely sharp at the beginning, and extremely flat near the middle and end of cycle. So it would drop from 12.1 loaded to the low 11s almost immediately, and then stay there. So I ran it down to 10.5v before landing. Total flight time: 16 minutes, 33 seconds, the last couple of minutes flying in level 1 alarm. Frankly, that's middling performance for a rated 5200, and about the same as my 4400s perform... Coincidence? The 10C rating is definitely true though. There's more voltage sag when you hit the throttle, and after landing at 10.5v, I read 3.69/3.72/3.71 (11.0v) on the pack. After 5 minutes, it had 3.73/3.76/3.78 (11.2v). My maddoog springs back faster and rarely rises more than 0.1v. And I was flying this thing around under 10.6v for two and a half minutes. Flight time is flight time, but I don't prefer a discharge profile that sits at landing voltage for minutes on end. On charge, 4027mah was reported put back into the pack. Which would be in line with a 4400mah run down to 10.5v. I did of course test directly against my Maddog 5400, which is a full 82g heavier at 397g, and MUCH wider. The Maddog, flown immediately after the Pro-Z-14, performed as consistently as it always does. Fairly linear discharge curve, first alarm at 19:30 (10.6v), landed still at 10.6v at 20:10. Pack voltages 3.69/3.68/3.71 (11.0v), followed by 3.69/3.73/3.74 (11.1v). I'll run a few more cycles and see if anything changes. Maybe these batteries need to stretch a bit before they get their legs? So far though, everything is looking like this is a low-C 4400mah pack. Which for $60 isn't bad, especially if you don't want to make your own packs, but it's no P2 pack... I have another pack coming from a different vendor too, maybe that one will be better. If not, at least these are light enough where I may be able to parallel them up and run them as duals on the Y6.