The sub-category of the product.

The way in which the device is worn.

What the product should be used for, and how it should be used (e.g. ambient temperature).

A headset is headphones combined with a microphone, or one headphone with a microphone. Headsets provide the equivalent functionality of a telephone handset but with hands-free operation. Types of headsets include single earpiece (monaural) and double earpiece.

The colour e.g. red, blue, green, black, white.

This is the ratio of signal intensity to noise intensity.

The technology that enables connectivity of the device, e.g. wired or wireless.

Ear coupling describes the way in which headphones or earphones stay attached to, or inside, the ear. There are three common types of ear coupling: circumaural, supra-aural and intra-aural. Circumaural headphones enclose your ears with large pads that suppress external noise. Supra-aural headphones are typically more lightweight and sit on top of the ears with small pads. Intra-aural headphones come in two basic designs and neither style sits on the head itself. The first are ear buds, which sit just outside of the ear canal, on top of your ear lobes. The second type is actually inserted directly into the ear canal and offers some external noise suppression.

The range of frequencies (low to high sounds) that the headphones can produce.

The effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance.

The characteristics of the microphone bulit into the device in terms of the reception of signals from all or just one direction, i.e. omnidirectional (better for concerts and the like vs unidirectional, more suitable for voice recording.

The range of frequencies (low to high sounds) that the microphone can pick up (detect).

The type of battery in the device, e.g. nickel–cadmium (NiCd).

The total time a battery can power a device for calls. As the device drains the battery during a call, the talktime left in the battery is diminished until the device is turned off or the battery recharged. The longer the talktime the less frequently you will need to recharge. Talktime, expressed in hours and minutes, is much shorter than standby time because transmission requires more power.

Approximate time required to recharge the battery from completely empty to completely full

Windows vesions wich can be used with the device.

Mac operating systems e.g. OS X can be used with the device.

The operating systems e.g. Android, iOS, that can be used with the mobile device.