1. Use TWIN (Check valve and Air stone), when the air pump is in use.
2. Especially, use TWIN when the air pump is set below the level of the water.
SPECIFICATION:
1.Air Stone, with plastic materials, can resist corrosion. In addition, the inside valve is made of silicon so it can extend the life.
2.TWIN, with the uniform air in, can make the double effect. Please feel the ease to use the patent valve.
3.TWIN can be used for any size of air pump.
