Linear flow-rate control balls from Plast-O-Matic Valves have metering or electronic positioning to provide precise process control. The Z-Cut ball design can be customized to provide virtually any required flow performance. Sizes are available from 3/8- to 4-inch and come in PVC, CPVC, natural polypropylene and PVDF. The modulating digital positioner offers autocalibrating and self-resetting functions. 973-256-3000; www.plastomatic.com.