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.

How long the cable is.

Country where the device is made. Aka Country of manufacture (COM).

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

The product has USB connector.

Bluetooth is a low-power radio technology developed to replace the cables and wires currently used to link or connect electronic devices such as personal computers, printers, and a wide variety of handheld devices including mobile phones. Because it uses radio-wave connectivity, a Bluetooth-enabled device has a constant, established connection to whatever browser it uses. This saves the user the trouble of logging on to check for emails or news updates, for example.

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.

Total harmonic distortion is a measure of non-linear harmonic distortion and is given in %. Non-linear harmonic distortions are signals which were not present in the original before the signal was converted by the headphones. These unwanted signals are caused by the diaphragm, whose movements do not precisely move in time with the electric signals that cause it to move. Unfortunately, this is a feature of all electroacoustic transducers. Although it cannot be completely eliminated, suitable steps can be taken to minimise it. However, the user is not interested in why this distortion takes place but in how great the level of distortion must be for it to become perceptible. According to the findings of several research projects, a total harmonic distortion of 1% in the frequency range of 100 to 2000 Hz is imperceptible. Below 100 Hz, the perceptibility threshold lies at 10%.

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).

Windows vesions wich can be used with the device.

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

The measurement or extent of something from side to side.

The distance from the front to the back of something.

The measurement of the product from head to foot or from base to top.

Weight of the product without packaging (net weight). If possible, the net weight is given including standard accessories and supplies. Please note that sometimes the manufacturer leaves out the weight of accessories and/or supplies.