I bought a few different drip tips as I was getting sick of the cheap ones wobbling in the tanks and RDA's the 'O' rings were not up to scratch, when this arrived I did think Ummmm its small, until I started playing with it and chucked it on different tanks ( SquapeR, Kayfun V4, Delta II, Lemo 2, Lemo Drop and the Nautilus ) it fits all of them perfectly, the double 'O' ring provides a perfect fit to all, this is not a wide bore for cloud chasing more of a tank drip tip, I am ordering another ready for the Titan arriving, would recommend excellent quality for a very reasonable price.