Control Valve, final control element changing manipulated variables; Actuator, operator providing power to move the stem; Valve Body, housing for the plug and seat; \(C_{v}\), capacity measured in GPM at 1 psi drop; Air-to-Open, 3 psi closed and 15 psi open; Air-to-Close, 3 psi open and 15 psi closed; Single-Seated, provides absolute shut-off; Double-Seated, equalizes pressure forces for large valves; Positioner, ensures quick action and overcomes hysteresis; Radiation Fins, protect packing from high temperatures; Extended Bonnet, prevents packing freeze in low temperatures; Butterfly Valve, rotates 90° for small pressure drops; Angle Valve, resists erosion in high-pressure service; Booster Relays, multiply volume or signal pressure; Cage Valve, uses a piston design for noise reduction; Linear, proportional travel-to-flow ratio; Equal Percentage, equal opening increments give equal percentage flow changes; Quick Opening, large flow increase at small openings; Solenoid, electromechanical on-off control.