The 6mm Top Hat Grommet provides a water tight connection using 6mm pipe with the 30 ltr & 47 ltr tanks. The 6mm Top Hat Grommet is positioned at the bottom of the tank, by firstly drilling a 10mm hole. The grommet is then inserted into the hole and a length of 6mm pipe is then pushed through the grommet. Push the tube through the grommet so that you can see the tube protruding inside the tank.