# Obtaining Good Contact Quality

Placement of the reference arm is critical for successful operation. The reference arm is the black tab which sits directly behind the left ear. The arm is designed to bend and may be positioned to suit the user. The two sensors on the reference arm must make contact with the patch of bare skin directly behind the ear. The sensor should be positioned so that it follows the angle of the rear of the ear, sits flat and parallel on the skin and has light, but definite pressure so that it is not displaced by moving the head. The following figure shows the available adjustments and the recommended placement of the sensor.

As the Insight sensors establish and maintain contact, it may take a minute or so for the signal quality to stabilize. If sensor indicators remain red or black, check that the sensors are making comfortable but firm contact with the scalp. Try parting the hair or gently working the sensor underneath the hair. Press and hold the sensor against the scalp for a few seconds to establish better contact quality. If the contact quality does not improve, try moistening the sensor with the rehydration solution.

Although the majority of indicator lights should be green, the detections will usually tolerate input if a few sensors are orange or red, even with one or two black sensors depending on the detection and which sensors are missing. Adjust the reference sensors so that their indicator lights are green.\\
