The IDP 013 Induction Loop Status Sign System from Williams Sound includes the T-sign, power supply, wall-mounting hardware (Sheetrock anchors, screws, and cable clips), external loop sensor (plugs into loop sign), and a small screwdriver. This system can be used to let your customers know that the loop system is working with a lighted status sign. The sign lights up green or red depending on the loop signal strength. Additionally, the sign is equipped with an internal loop signal strength sensor. An external loop sensor is also included.