This international Standard specifies requirements for high visibility clothing which is capable of visually signaling the user’s presence. High visibility clothing is grouped into three classes related to risk assessment. Garments shall comprise the required areas of background material and retroreflective material or alternatively shall comprise the required area of combined performance material. The area shall be measured on the smallest garment size available with all fasteners adjusted to the smallest configuration possible. Each of these classes will provide a different level of conspicuity, class 3 being the class that provides the highest degree of conspicuity against most backgrounds found in urban and rural situations in daylight and night time. The garment shall be made up of high visibility materials on all sides. To ensure visibility from all sides (360° visibility), it is important that horizontal retroreflective bands and fluorescent materials encircle torso, trouser legs and sleeves.
The performance class can be obtained using a single garment or a clothing ensemble, e.g. jacket and trousers. An assembly e.g. a classified trouser and a classified jacket, can be classified as an higher class if the assembly meets the minimum requirement achieved by the actually visible area when wearing the garment. This higher class shall be additionally specified in both the information for use and on the labels of both garments. Regardless of the area of materials used, a class 3 garment shall cover the torso and shall have either long sleeves with retro reflective bands or a full length trouser legs with retroreflective bands, it not both.

The minimum visible area requirements to achieve a garment classification are not to be reduced or compromised due to the presence of any logos, lettering, labels etc. Classification must be stated by a graphical symbol.