Advanced Precision CO2 Bubble Counter-Inline With Magnifying HolderHigh quality Inline Advanced Precision CO2 Bubble Counter With Magnifying Holder. Key Features: Clear and precise bubble formation allows you to count bubbles with ease. Built in check valve to prevent damage from water or CO2 liquid flowing back into your regulator. Durable magnifying holder to allow for attachment to the side of your tank or cabinet. Plastic cap for CO2 tube attachment. Made by Intense, a well known brand for reliable, most