These batteries performed noticeably better than the other 300mAh and 350 mAh batteries from competitors. If you're leisurely flying, the cheaper batteries will work, but if you want to have more power throughout the charge of the battery, these are better. On the downside, they cost more than the competition. Also, note that I soldered xt30 connectors because that was the connector on the drone we were using. So, I can't comment on the performance on the GNB27 connection