XPA-CB-14016-APO XPander Optical Smoke Detector with Sounder BaseXPA CB 14016 APO XPander Optical Smoke Detector with Sounder Base XPander optical detectors are recommended for use as general purpose smoke detectors for early warning of fire in most installations. The detector is calibrated so that XPander is highly reliable in detecting fires but has enhanced immunity to false alarms. The optical design operates on the well established light scatter principle, allowing it to respond to a wide spectrum of fires.