Towermax CO/4 for up to 4CO lines RJ-11/45. Protects four CO lines. Features 4 RJ-11/45 jacks through 2 ports (2 lines 2 equipment - pins 3 4 5 6 on each port). Use with Towermax KSU base unit. Includes two 7-foot phone cords. Clamping level 240 volts.