Starlac Industries offers Different Types of Unit. Starlac Industries is an ISO 9001: 2000 certified manufacturer and exporter of scientific instruments. It includes Zener Diode Unit, Silicon Diode Unit, Diode Valve Mounted, Mounted Triode Valve, Thermistor Unit, N-P-N Transistor Unit, Power Transistor Unit and Germanium Diode Unit. These units are housed on transparent base. They are incorporated with 4 mm. Colour coded sockets and circuit diagram printed for demonstration.