Fixing

Plates are usually fixed direct to a vehicle or to a plate frame that is fixed to the vehicle. Sometimes the plate frames contain advertisements inserted by the vehicle service centre or the dealership from which the vehicle was purchased. Vehicle owners can also purchase customised frames to replace the original frames. In some U.S. states license plate frames are illegal. Plates are designed to conform to standards with regards to being read by eye in day or at night or by electronic equipment.

Some drivers purchase clear, smoke-colored or tinted covers that go over the license plate to prevent electronic equipment from scanning the license plate. Although perhaps useful to those avoiding detection from police, these covers are not legal in the United States and their use is discouraged in other countries. The British system of traffic and DVLA number recognition system cameras incorporate filter systems that make such avoidance attempt unworkable, usually with infra-red filters.