Aquarium Equip Co2 Bubble Counter w/check valve for Regulator AQUARIUM fish planted tank Professional designed of hydrodynamic. It designed for screw lock on the CO2 tube, don't worry the tube loose off by the pressure, and caused damage. For easy maintenance, adopt the design of replacement of accessories. Dimension: L 3.5''(9cm) x W 0.98''(2.5cm)