Special designed for Planteded Tank, constant pressure design, high precision tuning, easy to realize 1 bubble/3 second Stainless steel material, never rust for 4/6mm air line. Provides convenience in distributing air flow up to different tanks. you can supply Co2 to aquariums, without having to purchase additional Co2 tank! Precisely adjust rate of air flow. Notice: if Bubble counter need, should order seperately Specification: W02-03 Color: Silver Material: aluminum alloy Package Contents: 1 * CO2 pressure reducing gauge Only above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is +/- 1-3cm.