GlobalEye Series includes 3 different form factors, 18 mm threaded combination, small block, and standard 18 mm tube. Each of these are available in background suppression, diffuse, retroreflective, and through-beam models. Background suppression sensors are able to sense targets and ignore objects behind them, where as diffuse sensors sense target when it reflects light back to sensor. Retroreflective types acquire object when it blocks light coming back to sensor from reflector.