The BB-XP is a wall-mount steel cabinet designed to house optional modules for the Notifier NFW-50X and NFW-100X fire alarm control panels. It ships fully assembled with a pre-installed chassis (Part # 18439) and features a left-hinged door. The cabinet provides 9 in. × 10.25 in. of usable internal mounting space for additional SLC, NAC, or communication modules beyond what the main panel enclosure can accommodate.