Brooks model 8500 series NRS (non-rising stem) control valves are designed specifically for extremely low-flow gas and liquid applications. Straight and 90 degree angle pattern models in brass or stainless steel are available. They feature a means of adjusting a sliding tapered needle which prevents sticking. Theses valves are particularly suitable for precise control and possess a high turn-to-lift ratio. The flow is constant for any given stem position.