Towermax CO/4x4 for up to 4 COlines, RJ-11/45. Protects four CO lines. Features8 RJ-11/45 jacks through 4 ports (4 lines, 4 equipment - pins 4,5 each port). Use with Towermax KSUbase unit. Includes four RJ-11 7-foot phone cords. Clamping level 240 volts.