The Patton Model 552-D8 installs between an incoming telco line and dial-up/leased line/xDSL modem, ISDN modem (a.k.a. TA or NTU), T1/E1/PRI or DDS and intercepts harmful telco line transients before they cause hardware damage. Surge energy is then diverted to nearby chassis ground through a braided metal strap.