Hydro Flow Top Hat Grommet 1/2 Inch, Bag of 10 These grommets can be used to replace old, worn top hat grommets in your hydroponic system and can be a valuable solution when building your own garden system Top Hat grommets have a straight side wall for easy installation When the fitting is inserted into the grommet, the wall is pushed against the whole surface to create the seal Top Hat grommets have a straight side wall for easy installation When the fitting is inserted into the grommet, the wall is pushed against the whole surface to create the seal Made of reliable, black rubber