This tube is an odd device in that it uses a tube with on OD of 18.6mm which is is size not available to us. The wall thickness is 1.5mm and the ID 15.6mm (OD - 2xWall). We do have a tube size of 18.0mm x 1.2mm which is the same ID and by the way this tube mounts ID and Length are the important parts. This means this tube will be slightly smaller OD than the end caps of the device. This isnt a bad thing in that if a PV is tipped over on a flat surface the glass wont hit but it may be an aesthetic concern for some. The difference is only 0.30mm or about 0.012" just to give an idea as to the small change in OD. Second oddity with this device is the formed silicone seals. This is one of those proprietary parts like the eLeaf Lemo and Lemon Drop seals and sadly it will probably mean tossing devices for many if alternates such as regular orings or flat washers are not found for these atomizers. This is one place where the consumer can work towards forcing makers of these devices to design with you and long term use of your gear in mind. Luckily we were able to get an ID match for the glass on this so far at least the time being we will be able to provide glass replacements. Thanks go out to one of our customers for providing a tank for measuring, I am sending a couple of tubes out to you along with the the tube you sent.