Introduction: The HR Series High Resolution Control Valves contain unique design features that make them the ultimate choice for precise low flow control, including: Spring loaded, non rising adjustment stem with 56-pitch thread provides smooth, non-reversing flow characteristics and 15-turn resolution; Non-rotating stainless steel valve pin with precision ground flat gives exact control; Valve pin o-ring guarantees positive shut-off without stem damage; Self-lubricating orifice liner assures long life; Seven available needle tapers expand valve capacity.