PACLOCK's UCS-81A is engineered specifically for standard swing door trailer handles that are found on truck trailers, reefer trailers, toy haulers, car trailers, horse trailers, and equipment trailers (does not fit intermodal containers). The lock is machined in the U.S. from 6061 aircraft-grade aluminum and features a patent pending bolt cutter-proof hidden shackle design. All brass, aluminum, and stainless steel components render the lock rustproof. 6-Pin technology (more than the industry standard 4 pins) provides over 20,000 unique key codes and makes duplicate key combinations extremely rare, meaning that your key number is virtually unique to you. Stainless steel spool and serrated security pins make the lock pick, bump, and drill resistant. Includes the PAC-BAND, a field-replaceable silicone cover to protect the cylinder from the elements. Also features the PAC-TETHER – a cable that can be crimped to keep the lock fastened to your trailer door so that you’ll never leave it behind. Please be aware that the TL81A will not work on intermodal container doors nor any swinging handle hasp that has an extra “rib” on the handle. For these situations, please purchase the “UCS-82A”. CNC machined for U.S. precision and reliability, the lock body exceeds /-0.003” tolerances for repeatable quality.