Detector, Overall Length 4 in, Accessory Type Responsive Alignment Target, Overall Height 4 in, Overall Width 1 in, Compatible with Level Type Levels, Material Plastic, Color Black, Compatible with Manufacturer Model Number 3521-21, 3522-21, 3622-20, 3622-21, 3632-21, Includes Responsive Alignment Target Only, Number of Pieces 1, Thread Size Not Applicable, Voltage Not Applicable