The Viavi JDSU T-BERD 2000 4126 LA SM Fiber OTDR is a powerful and reliable Optical Time Domain Reflectometer (OTDR) designed and manufactured by Viavi Solutions, formerly known as JDSU. The T-BERD 2000 4126 LA supports dual-wavelength testing at 1310nm and 1550nm, enabling users to assess different sections of the fiber with a single device.