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) 11/2" 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. heavy chassis, packed with 4-page owner's manual, weight 1 pound.