AQUATEK CO2 Brass Bubble Counter with Integrated Check Valve Designed to be compatible with AQUATEK CO2 Regulators (Models: Basic R-76, Premium R-76-1 and Mini R-78) Attaches directly to AQUATEK regulator without tubing or extension Built-in check valve prevents back-siphoning and protects CO2 system Be aware of Knock-Off. Aquatek is the sole authorized distributor to sell this bubble counter on Amazon. Be sure to purchase from Aquatek and fulfilled by Amazon (Sold by Aquatek and Fulfilled by Amazon, not from third-party seller) for compatibility and genuine parts made of highest quality. Look for original package and color (shown in the product images)