The Depth Ray liquid-level monitoring and control system from Eldredge Equipment Services can operate in vacuum or pressure, or in heavy material in mobile or stationary tanks. It contains no rods or floats and is constructed of chemical-resistant components. It features a wireless remote and optional controls for valves and alarms. Its operation is unaffected by most foam or density. It can be installed easily in any tank or container and exceeds DOT requirements. Several models and options are available. 800/220-2052; www.depthray.com.