Alumina airstones - three times stronger than white silica airstones! Produces a finer bubble with no increase in pressure.* Inlet fittings are set into the body of the diffuser, making them much less likely to break or twist loose* Higher density means self weighting* Cleanable with muriatic acid or chlorine* More resistant to ozone* Creates finer bubbles for increased aeration efficiency with no increase in pressureAvailable in the following:Part NumberDimensionsFittingAS151.5"" x 1.5"" x 1.5""3/16"" barbAS3251.5"" x 1.5"" x3""1/4"" barbAS6501.5"" x 1.5"" x6""1/2"" MPTAS9501.5"" x 1.5"" x9""1/2"" MNTAS12501.5"" x 1.5"" x12""1/2"" MPT AS1250 - EasyPro Alumina Airstone