# The Traffic Signs Regulations and General Directions 2016, Paragraph 7

Extent: E+W+S

(1) The triangle must be legibly and permanently marked with the marking designated as an approval mark by regulation 4 of the Motor Vehicles (Designation of Approval Marks) Regulations 1979 and shown in item 27 of Schedule 2 to those Regulations.
(2) The surface coloured red and marked A must be reflectorised;
(3) Not more than 15 square centimetre of the surface marked A may be obscured by constructional components;
(4) The surface coloured red and marked B must be fluorescent;
(5) The surface marked C must be either—
(a) entirely reflectorised; or
(b) a combination of reflectorised and fluorescent;
(6) Not more than 10 square centimetre of the surface marked A may be obscured by constructional components;
(7) In the case of the triangle provided for at item 33—
(a) the surface coloured red and marked A must be reflectorised;
(b) the surface coloured red and marked B must be fluorescent and have an area of not less than 315 square centimetres;
(c) the edging coloured red and marked C may be omitted.
(8) Corners of a triangle must be radiused.
(9) All sides of a triangle must be of the same length.
(10) The reflectorised areas of the surface may be internally illuminated provided that such illumination is steady, presents a uniform appearance throughout that area and does not impair the retroreflecting properties of that area of the surface.
(11) The triangle must not be illuminated through external illumination.

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Source: https://www.legislation.gov.uk/uksi/2016/362/schedule/13/part/7/paragraph/7 (the official version)
Page: https://openlegislation.uk/traffic-signs-regulations-and-general-directions-2016/schedule-13/part-7/paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.