The IRW-2C: 2" Infrared Inspection Window is an indoor/outdoor Rugged Aluminum IR Window (2.87"/73mm diameter) for safe and easy inspections. FLIR IR Windows now offer a solution to help reduce exposure so you can perform scans safely, more efficiently, and confidently while complying with NFPA 70E requirements. With PIRma-Lock tried and true locknut technology makes FLIR's IR Windows' self-grounding locking ring an IR windows first, with teeth that bite tight to the inside of the panel.