The 2151 Plug-in Photoelectric Smoke Detector offers superb performance and reliability in a profile which is just 1.6” (4.2 cm) deep. The 2151 has a sleek low-profile design and can be used with a variety of different adapter bases in several wiring configurations. Other features include: low current draw, stable performance in high air velocities, built-in tamper resistant base design, remote LED option, removable cover, and built-in test switch.The 2151 is designed to meet the performance criteria designated by UL. This chamber is protected by a fine mesh screen which can be cleaned or replaced. Additional key features include a variety of mounting bases, and a full line of accessories.The 2151 photoelectronic smoke detector contains a unique optical sensing chamber designed to sense smoke particles produced by a wide range of combustion sources. A custom integrated circuit incorporates signal processing to reduce false alarms. provides good performance at higher air velocities.