1. the reference index or luminous intensity
The reference number (Ref.) is a value that refers to driving lights. According to ECE regulations, this reference number must not exceed the upper limit of 100 per vehicle. Here, the two values of the standard high beam (left and right main headlight) are counted in addition to the values of other mounted high beams. The value is entered on the lens of approved headlights. This means if 4 headlights with a reference number of 25 each are installed, the lower two will go out when switching on. Then there are no problems. If you do not couple it with the normal high beam and put it on an extra switch, you should consider the following. The switch or display in the vehicle must shine blue and be in the direct field of vision of the driver. Here you find headlights with the Ref. 25 number
2. ECE approval Lighting equipment on the vehicle must bear an E-mark.
This is a marking of components on the vehicle which are subject to approval. In addition, the mounting height and position of the headlamps must be permissible and correctly selected.