Unshielded telephone wiring is very susceptible to natural and man-made
interference as well as overvoltage influence. Modern solid-state telephone
equipment, computer modems, telephone patches and interconnection equipment are
all easily damaged by fast rising transients caused by lightning discharges and
electromagnetic fields.

Model 340 Series suppressors / filters are combination multi-stage units that
isolate telephone circuits, providing hybrid dual-action voltage protection
with gas-discharge and metal oxide componentry, and noise / RF filtering by
twin-stage decoupling/bypassing. May be installed indoors or outdoors at
telephone line junction connections to building entry, for overhead or buried
lines.

Measuring (HWD) 1-1/2" x 3" x 3", models are available for direct hardwiring
with screw terminals or all modular. Both are 4-wire and designed for one or
two line services, polarized (input and output), work with any telephone brands
or models. Ground terminal connection required to nearby ground rod or earth
electrode, Units are fully shielded assemblies in standard I.C.E. havy
chassis, packed with 4-page owner's manual, weight 1 pound.