JBL ProSilent a400 is a new extremely quiet air pump generation for aquaria with a air output of 400 litres per hour. The pump operates at an extremely low noise level due to a completely new construction design incorporating a silencer. JBL ProSilent air pumps are scarcely audible. Precision workmanship and high quality materials ensure long working life. Place the JBL ProSilent pump above the water surface for protecting the pump for flow-back of the water. If the pump is located below the water surface, it is recommended to install a non-return valve in the air hose to the pump.technical data JBL ProSilent a400:- whisper quiet (- pump output max. 400 l/h, adjustable- power consumption 5.5 W- head pressure >180 mbar- 2 connections for 4/6 mm air hose- 90rotable air connection- for aquarium from 200-600 litres- incl. 2x 2 m air hose, 2 non-return valves and 2 air stones- 4 years guarentee