The CFL class 4000 is a variant of the BombardierTRAXX locos found working across Europe. Within Luxembourg they work on the local passenger services (crossing the borders into France or Belgium as necessary. They also work freight traffic. Their 15 kV capability allows them to work across the border to Germany. Even though they are capable of running in France, they are not allowed to do so for security reasons.
Their slab sided body work has been used for advertising.