The 4925A Bit Error Rate Test Set not only performs the standard bit and block error tests, it measures errored seconds, percent error-free seconds, timing delay, and parity errors. increased flexibility is afforded by providing you wity the ability to verify various elements of Level 1 protocol in the form of a complete breakout box. You can manipulate and monitor individual signal lines on the RS-232C/V.24 interface or crosspatch any line from the DCE side of the interface to the DTE side of the interface.