Motor vehicles which, due to their construction, cannot drive faster than 40 km/h must be marked with a rear warning marking in accordance with UN regulation ECE 69.
Appearance and further requirements for slow-moving vehicle rear warning signs | are based on ECE 69. As there are two versions of the directive - 69.00 and 69.01 - the ECE 69 sign can be used in two reflectivity classes: According to ECE 69.00, reflectivity class RA2/B is sufficient, while the newer version of the directive (ECE 69.01) requires the higher reflection class RA3/C.
The slow-moving vehicle sign is triangular in shape and consists of a retroreflective frame with a fluorescent core. Thus, the sign can draw the attention of other road users to the slow-moving vehicle during the day and at night and ensure that it is better seen.