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Single-Line Tester

Tests USOC and EIA/TIA T568A/B cabling.


Please call 877-877-2269 for a replacement product or part.
Extended Double Diamond™ Warranty Available (3 Additional Year)

Product Features

  • LEDs alert you to shorts, opens, reversals, and miswires at a glance.
  • Built-in modular jacks for three different cabling systems—no need for adapters.
  • Accurately verifies the integrity of 2-, 3-, and 4-pair voice and data channels.


The Single-Line Tester's LEDs immediately alert you to shorts, opens, reversals and miswires at a glance. Simply snap and lock the master and remote together when not in use. The lightweight, rugged, and impact-resistant unit comes with a 9-volt alkaline battery.

Tech Specs

Connectors Master unit: (3) RJ-45; Remote unit: (3) RJ-45
Indicators Master unit: (4) LEDs; Remote unit: (8) LEDs
Power (1) 9-V alkaline battery (included)
Size 1.6"H x 2.3"W x 5.5"D (4.1 x 5.8 x 14 cm)
Weight 0.5 lb. (0.2 kg)
NOTE: This device is designed strictly to test continuity and should never be inserted into a live circuit.

* Technical specification weight is the unit weight. It is not the packaged shipping weight. For shipping weight, please contact Black Box customer service at 877-877-2269.


Double Diamond Warranty

Extended 1 Year Warranty Available

Protect your purchase with an additional 1 Year Double Diamond™ warranty!
Cost: $12.60

Extended 3 Year Warranty Available

Protect your purchase with an additional 3 Year Double Diamond™ warranty!
Cost: $25.19


Double Diamond™ Warranty (Standard)

Take the risk out of equipment purchases with the Double Diamond™ Warranty from Black Box Network Services.

The Double Diamond Warranty is our warranty that protects your Black Box® brand products* from accidental damage, including drops, water, and power surges.

The Single-Line Tester comes with a standard 1 YEAR warranty already included.

During the warranty period, Black Box Network Services will repair or replace your damaged equipment within one week of receipt at NO CHARGE!*

Plus, get an Extended Double Diamond Warranty.

You can also extend your warranty or protect a previously purchased Black Box® brand product** for an additional year—for only 10% of the purchase price! Or, extend your coverage for a full three years for only 20% of the purchase price!

Ordering an extended warranty is easy: When viewing a product in your shopping cart, just select the one or three years of additional coverage in the dropdown menu under “Warranty Options.” For details, contact Customer Service at 724-746-5500.

* Warranty subject to certain exclusions and limitations ** Certain products may not be eligible.

What’s more, we also have a 45-day return policy. Simply call Customer Service for a Return Authorization (RA) number, return your product in new condition and in the original package, and receive a full refund.