Good air exchange is the key to a successful grow room. These RVK 150mm A1 fans, made by Lti System air of Germany are quiet running and extremely reliable. They are designed to run 24/7 and hardly ever go wrong!! They are ideal for connecting to our range of carbon filters that we stock. RVK fans come in 2 version A1 and L1, L1s are more powerful than A1s - bear this in mind when selecting your filter!