British Standards (BS)
A British Standard sets a benchmark for quality of goods and services. These are produced by the British Standards Institution (BSI).
A Royal Charter grants the BSI the authority to prepare, revise, alter and amend the standards “as experience and circumstances require.”
Products and services that BSI certifies as having met the requirements of specific standards are awarded the BSI Kitemark™, which can be found on product packaging and the products themselves.
BS 3621 and EN 1303:2005
BS 3621 is a British Standard relating to thief-resistant locks.
EN 1303:2005 is a European Norm relating to cylinders.
Together, these standards benchmark the minimum performance for locks and cylinders on external or entrance doors to be acceptable to the Association of British Insurers (ABI) and the police service.
These standards do not guarantee the resistance of the door to which they are fitted; the effectiveness of the lock also depends on the quality of the door, frame, and other hardware (that is not tested to this standard), which may fail before the lock or cylinder.
European Norms (EN)
A European Norm (EN) is a standard that outlines the rules, guidelines or characteristics required of products, services or systems, and has been adopted by one of the three recognised European Standardisation Organisations (ESOs): CEN, CENELEC or ETSI.
Products and services successfully tested against the benchmarks in the relevant standard are said to “comply with the requirements of the standard”, and will be accordingly marked on the packaging.