The Schneider Electric (Barber Colman) PND-2-1 Diaphragm is a flexible control component designed for use in pneumatic HVAC systems. It operates by responding to air pressure changes, expanding or contracting to facilitate precise control of actuators and valves. Commonly used in air handlers, control panels, and building automation systems, it supports accurate pressure regulation. Its durable construction enhances reliability, improves system responsiveness, and ensures consistent performance, making it essential for efficient and dependable HVAC control operations.