The VELOCICALC® Model 9565 series are portable, handheld, Multi-Function Ventilation Test Instruments featuring a menudriven user interface for easy operation in your local language. On-screen prompts and step-by-step instructions guide the user through instrument setup, operation, and field calibration. The 9565 also features an ergonomic, overmolded case design with probe holder and a keypad lockout to prevent tampering during unattended use. These instruments are available with or without a differential pressure sensor and are designed to work with a wide range of plug-in probes.