The GRAV Gravitron V2.0 - Gravity Bong UK
This is the world's first all-glass gravity bong, and it's been upgraded and improved for even better performance. The glass is five times thicker than before, and the silicone grommet has been replaced with a platinum-cured version for a tighter seal. The 19 mm female ground joint now fits any 19 mm male bowl, and the flange at the top of the neck makes lifting the bottle easy.
To use the Gravitron, fill the base halfway with water. Then pack the bowl with dry herb and insert it into the joint at the neck of the bottle. Light the bowl and lift the bottle at the same time.