The Dutch ART Foundation focuses on theft prevention for two wheelers. They use the so-called ART quality mark, which is awarded to a range of scooter and motorcycle locks.
For certain Dutch insurance companies the use of an ART-certified lock is a precondition for insurance against theft.
How the Quality Mark works
Only locks for two wheelers that meet the set requirements can be awarded the Quality Mark.
The locks are divided into different categories, such as chain locks and ring locks. In addition, a star system is used. The more stars a lock has, the higher its preventive value and the better it protects against theft. A lock with five stars has the most preventive value.
Which lock should I use for my bike?
In general, the following advice applies:
1 star is minimum security (discourage, rather than secure)
2 stars for bicycles
3 stars for mopeds and scooters
4 stars for motorbikes (on the road)
5 stars for motorbikes (stored at home)
More information can be found on http://www.stichtingart.nl/en.