This is a tiny but necessary item. It came properly packed and in excellent condition.

Didn't com with any instructions for installation. Installed in. Worked like a regular jack. Didn't seize the line (like I expected it to), for use a lifeline alert system. (I guess I didn't install it right.)

Description is slightly misleading... An RJ31x jack allows a reliable way to insert an alarm system that has line seizing capabilities between the building's incoming phone line and the various phones throughout the building or house. In normal conditions, the alarm system simply lets the phone circuit pass, and in an alarm condition it seizes the line so it can call the monitoring centre whether someone is using a phone in the building or not. Should the alarm system malfunction, removing its cord from the RJ31x jack restores normal operation of the phones. Line seizure is a function of the alarm equipment burglar/fire, some personal/medical alert systems with the proper cordset, etc, not the RJ31x jack.