The LR3D Controller combines three essential devices in one physical container, making it a lightweight, space-saving, and cost-effective alternative for any aircraft electrical system, while also improving safety of flight.  First, the LR3D operates as a quiet, linear regulator, generating little audio or radio noise (in contrast to switching-type regulators). Second, it provides a vital safeguard for your aircraft electrical system with a solid-state, crowbar over-voltage protection circuit. And third, the LR3D Controller functions as an important low-voltage monitoring and warning system. Used on externally-regulated, 28V alternators using circuit type “B” (one field lead grounded directly). This 28V regulator will NOT work with a B&C alternator. For Experimental Aircraft ONLY Installation Note: Select a location for mounting that will protect unit from heat, vibration, and water. The pilot side of the firewall, or inside the cabin near the instrument panel, is recommended.