Got a good deal on a couple of sony VTC5's at a local vape shop, and they're great. I was content with the VTC4's, but these we're being sold at the same price. I bought a pair, not expecting a huge difference. These things last damn near all day. I use a patriot rda on a stingray clone and I go through about 3 VTC4 batteries a day, with the VTC5 MAYBE changing them 1 time at night. They stay at 3.7 through just about their whole range and I've had zero issues. Highly recomend.