Extech LS320FC Fiber Optic Laser Light Source provide high stability and features: Temperature compensated laser light sources with 1310nm and 1550nm output supply -10dBm of stable optical power into single mode fiber; Provide 50dB measurement range when used with FiberMeter or MicroMeter; Single battery provides over 60 hours of operation; Rugged, splash proof case; Single switch operation; FC connector.