Green Leaf Aquarium CO2 regulator. Regulator works perfect used a total of about two years. Bubble counter needs to be replaced. Unit has all original components since being built new from Green Leaf Aquariums. This is a very high quality unit and was their professional line. Parts are available since Smith is widely used for many other uses. This is not one of the cheap imports and is in like new condition with the exception of the bubble counter which needs to be replaced or eliminated depending on your preference of your configuration needs. Tanks not available I just hooked one up in one of the photos to show it works. $175 shipping included.