The “RD-77S-2516” is PACLOCK's high-security solution for standard 2-5/16” trailer couplers – engineered from top-grade materials for strength, simplicity, and all-weather reliability. PACLOCK's patent-pending two-piece design integrates the lock body directly into the protective shroud, eliminating the need for a separate puck. That means faster installs, fewer parts to manage, and less frustration – especially in harsh conditions like rain, mud, or snow. At the heart of the lock is PACLOCK's patented 304-grade stainless steel cone puck – a customer favorite for its superior corrosion resistance and toughness. Unlike the 303 or 302 grades used by competitors, 304 resists cracking and deformation under hammering and prying. It can also work-harden during poorly executed drilling attempts, making frontal attacks even harder to pull off. The cone shape deflects drill bits before they can grab – a key defense feature. The shrouded ¼-inch steel housing provides added protection from cutting and blunt force attacks. A zinc-plated base layer beneath the powder coating keeps rust at bay – even if the outer finish is damaged. With PACLOCK's Every Lock, One Key (ELOK) capability, you can key all your PACLOCKs alike – from your coupler to trailer doors, hitch receivers, latch pins, YETI coolers, toolboxes, and more. Innovation That Secures What Matters. PACLOCK builds locks that perform when it counts – smart designs, serious materials, and unmatched versatility for people who take security seriously. Combined with PACLOCK's RD cylinder technology, the RD-77S is ideal for customers requiring the highest level of security.