From the manufacturer:
ARGUS Copper Box v3
The ARGUS Copper Box is intec's expansion for the ARGUS 15x and ARGUS 16x xDSL combi testers. With this USB Box, it is possible to, on the one hand, detect dangerous voltages and currents before they can cause harm and, on the other hand, safely determine the physical characteristics of the line. 
This latter feature is of particular advantage when it is not possible to synchronize a DSL line or when the data rate achieved on a line is so low that there is reason to suspect that asymmetry (an unbalance), interference or mechanical issues are causing problems on it.
The compact Copper Box is attached to an ARGUS tester using its USB host interface. Using the ARGUS's graphical user interface, the user can select the Copper Box and quickly and easily perform all the supported measurements.
The ARGUS Copper Box has three standard banana jacks plus support for an additional connection for customer-specific requirements. To ensure safety in both the lab and the field, the standard jacks are equipped to accept 4 mm shrouded banana plugs.
Other technical characteristics of the Copper Box:
 Using the autotest enables you to test automatically withvarious predefined measurement profiles.
 Using the DC voltage measurement, it is possible todetermine the type of access (e.g. ISDN or POTS), supplyvoltage and any interference voltage.
 With the AC voltage measurement, it possible to detectdangerous interference voltages.
 With the aid of the capacitive symmetry, it is possible todetect anomalies in cabling. These anamolies can lead tosignal distortion or transmission errors.
 Capacitance measurements will indicate any interruptions in the line and can determine the typical inputcapacitance of the connected equipment. Furthermore, thesemeasurements can be used to assess whether the wire pair isunbalanced.
 Isolation resistance measurements can be used todetect damaged cable isolation, moisture in the cables oroxidized contacts.
 With the aid of the resistive symmetry, it is possible todetect anomalies in cabling. These anamolies can lead tosignal distortion or tranmission errors.
 Loop resistance measurements can be used to detectshort-circuits as well as to estimate the line length.
 DC current measurements can be used to detect emergency, external or normal supply as well as to determinewhether the line is too long or interrupted.
 Symmetry measurement (LCL): This measurement at afrequency of 1 MHz can be used to assess whether the wirepair is unbalanced.
 NEXT measurement: Measures the Near-End Crosstalk ata frequency of 1 MHz.
 Use of the signature detection to evaluate the signature orPPA from the subscribers line.
 Use the remote kit to control the far end of the line andchange it to the desired state.
All of the measurements can be performed as automatic TRGmeasurements (Tip (a), Ring (b), and Ground) with a high degreeof accuracy.
The compact ARGUS Copper Box weighs just 160 grams andthanks to its high-quality plastic case it can shrug off beingdropped as well as most impacts and other mechanical abuse. Inspite of its performance and the high voltages that it applies forsome measurements, the Copper Box still exhibits anexceptional operating time since it draws its power from theARGUS tester's high-powered lithium-ion battery pack.
The Copper Box was designed with an eye to compatibility so itcan be used with a number of testers. As a result, an installationteam using a variety of ARGUS testers can each extend theirtester's capabilities using these boxes and all their features.Consequently, the testers need not be sent in to have theseadditional features added. The USB Box can be tied togetherwith the tester using a specific shock absorbing rubber jacket.You can also use your PC to get free updates for the Copper Boxquickly and easily.