I vaped on this carto all day yesterday. My son dropped by and vaped on it . I vaped all night on it and didn't think it would ever run out. The vapor was the same (clouds) on the last puff as the first puff. Well it finally needed a refill and I wanted to see what was inside. First off the white cap is thicker and there is no tephlon ring inside. I still couldn't see why it lasted so long so I put it up next to an 808 and V4L and it is indeed longer plus if you take into consideration that 808 /V4L have an indentation on the battery end the 510 doesn't that makes even more room. I can only get, on a used 808/V4L carto, about 15 drops at the very most on a refill. This 510 drank up a whopping 30 drops before it's thirst was slaked. Thats twice the copacity of the others. This was the best money I ever spent and I'm glad they had the $7.50 deal on a box or I would probably have missed such a great product as I'm knee deep in cartos.