The HDA 300 is a pair of closed, dynamic headphones designed for use with audiometers. Suitable for high frequency audiometry. High passive ambient noise attenuation - patients only hear what they are supposed to hear. Excellent repeatability of readings. Excellent comfort fit even for long testing periods thanks to soft, replaceable ear pads and two padded headbands. Single-sided cable for tangle-free sessions. Equipped with two mono plugs for immediate use. Foldable ear cups for portable use and easy storage. Design approved by the PTB (German organisation for type approvals, a national standards organisation similar to the British Standards Institute or the American National Bureau of Standards).