Feature: 1. The refiner can make the CO2 bubbles more uniform, better diffuser efficiency. 2. There are there sizes for you to choose from, meeting your different needs. 3. Designed with bubble recording function, easily accounting the amount of the added CO2. 4. Adopt fine workmanship, sturdy and durable, long service life, not easy to damage. 5. Small size and lightweight, practical CO2 refiner, adding beauty to your fish tank. Specification: Item Type: CO2 RefinerCondition: 100% brand newMaterial: GlassColor: TransparentApplication: Medium and large water plant tankInstruction: It should be placed on the bottom to enhance the dissolving effect.Model: V-AP-028, V-AP-029, V-AP-030 (optional)ModelHeightDiameterSuction Cup DiameterV-AP-0285.9cm/2.3in1.9cm/0.75in2.1cm/0.8inV-AP-0297.2cm/2.8in2.5cm/0.98in2.1cm/0.8inV-AP-0308.2cm/3.2in2.6cm/1.02in2.1cm/0.8in. Package List: 1 x CO2 Refiner1 x Suction Cup