Red Eye Tek knows a thing or two about smoke diffusion, and the 10-arm flush mount diffuser downstem is a perfect example of that knowledge being applied to create the best smoke experience possible. Need a simple way to add some serious smoke diffusion to your bong or water-pipe? A 10-arm perc design for a downstem that your bong needs anyway will do the trick, and for an affordable price. Extra wide. 29mm ground joints. Available in assorted lengths.