CO2 Bubble Aquarium Bubble Counter with Check Valve Diffuser Atomizer ReactorFeatures:1. High quality and low price2. Small and compact3. Easy to install and replace4. A non-return function to prevent the backflow when the pressure changes5. Made of tough material for long-term use Specifications:1. Material: Aluminium Alloy ; Acrylic2. Color: Silver3. Dimensions:Single-head��(3.11 x 0.79); / (7.9 x 2.0)cm (L x Dia.)Dual-head��(3.23 x 0.82); / (8.2 x 2.1)cm (L x Dia.)4. Net Weight:Single-head: 1.30oz/37gDual-head: 1.41oz/40g style��1#��Single-head2#��Dual-head Included in the Package: > 1 x Bubble Counter ( Single-head / Dual-head as your choose )