5 Lever BS Deadlock 64mm. British Standard BS3621 Rated Dead Lock used as a matter of course by the national house builders. This lock provides a high degree of security and carries a 25 year mechanical guarantee. It has been CE and Certifire tested. Suitable for use in all domestic, industrial and commercial environments. As long as the recommended cleaning process is followed, the stainless brass PVD long-life finish offers a 25 year finish guarantee, which renders the surface impervious to damage in normal use including oxidation and abrasion. So your product will stay as good as new, even in coastal areas.