The 75 won't take a 25mm tank. The Mega and Dual will, but the Dual has one of those "glad to see you" pocket bulges
That's right. The Pico 75 battery cap is the culprit. I also have the Pico dual and it's a good around the house vape, but it's a monster for pocket carry. It's like one of those old coffee table cigarette lighters (too big for a pocket so guests wont walk off with it!).