There are tons of needle valves available in the market today but most of them are not intended for very low flow co2 injection that we need for the planted tank hobby. Unlike sub-standard needle valves installed on cheap co2 regulators, our Fabco NV-55 needle valve provides a steady flow of co2 and is able to maintain constant flow rate(i.e. bubble count) throughout the co2 injection on/off cycle. We also offer the smaller and cheaper(but decent) SMC needle valve. Once set, the SMC needle valves reliably holds the flow rate for a set and forget co2 setup.