Rocking Piston Aeration Kit (1/2 Hp, No Cabinet) This Complete Kit for 1.5 acre ponds Includes a 1/2Hp Rocking Piston Air Pump, a 3 way manifold with a safety valve, three 100 ft rolls of 3/8" weighted tubing, and three 9 inch diffusers with bases The manifold includes an attached is a pressure relief valve which opens at approximately 25 psi to prevent damage to the compressor The self-weighted air hose is very heavy duty and pliable. It is stronger, thicker and heavier than other brands. It will not crush or kink and can handle freezing temperatures The 9 inch EPDM disc diffusers are designed for industry heavy duty installation and offer the lowest back pressure in the market, only adds less than 6 inches of water depth back pressure, allowing you to utilize your air pump in the most efficient way