Abstract: An extendable edge reference tool is disclosed. A first segment having a extending end and a receptacle end is provided. The receptacle end includes a coupling mechanism for joining a second segment using an over-center locking force to secure said second segment to said first segment. This tool provides for a useful continuous reference edge over extended distances through adjoining segments. Each segment is suitably compact to be easy stowed. The segments are useful individually. The segments can be joined to extend tool to lengths useful in common construction tasks.

Abstract: A leak detector is disclosed. The optical leak detector may include a sensor module for transmitting and receiving signals corresponding to the surface level of a monitored fluid and include leak detection logic for detecting a leak signature. The leak detection logic may be configured to determine if fluid contained in a tank is in a non-full state outside of a normal state and activate an alarm.