Check the listing for details. Matala Hakko Membrane Air Diffuser Assemblies with Heavy-Duty Base. Condition: New. Listed at 85.00 USD. Matala Hakko Base Air Diffusers are membrane air diffuser assemblies that feature heavy-duty plastic bases with soft edges. These bases are hollow so that they can be filled with sand or gravel, eliminating the need for bricks and straps to get the diffuser to sink. Two sizes of bases are offered: the small base can accommodate one or two diffusers, and the large base can accommodate two or four diffusers.Heavy-duty diffusers produce medium bubbles, reducing back-pressure on the pumpAll base units come with multi-barb to attach to 3/8", 1/2", 5/8" or 1" air hoseModel #Size of BaseDiffuser SizeIncluded DiffusersRecommended Air Pump SizeMDB11Small9"125-80 LpmMDB11-12Small12"1100-120 LpmMDB12Small9"280-150 LpmMDB12-12Small12"2120-200 LpmMDB22Large9"280-150 LpmMDB22-12Large12"2120-200 LpmMDB24Large9"4 MDB24-12Large12"4 Discs need very little or no maintenance. Simply rinse the disc with clean water. Use bleach if your diffuser needs extreme cleaning.