AmbitionZ VapeR and Timesvape Diesel RTA does sport an overall diameter of 27mm, but does taper down to 25mm, so it'll look great on your larger mods. In addition, it has a maximum e-juice capacity of 2ml or 5ml with the included bubble tank. Also, filling it is quite easy thanks to its top fill design. At the top, you'll find a wide bore 810 drip tip, which is replaceable so you'll be able to use your favorite custom 810 drip tips. A protruding gold plated 510 connection is at the bottom, ensuring excellent conductivity.