My funnel bowel fits very tight and no need for adaption. However, the bowel that came with the Hookah was loose and I employed the paper towel method. Cut a strip of paper towel about 1/2-1 inch wide and about enough length to wrap around the grommet twice. Wrap it around the bowel grommet and then slide the bowel down over the paper towel "spacer" if you will. Adjust the length of the paper towel accordingly to give yourself a tighter fit as needed. Works great.