This Proven Industries 400A XL blue puck lock features a step back and has a larger opening in the back to fit rear and side enclosed trailer doors. Keyed alike. Features a hidden shackle, and comes with 2 keys. It's made from aluminum with a 6 pin brass cylinder. It is the same size as the 400A, but with a larger shackle opening, making it perfect for use with toy haulers and enclosed trailers. This also makes it possible for the puck lock to be used in place of a padlock more easily. As part of the Proven Industries 3 part coupler lock, it prevents theft by securing not only the coupler but also your safety chains. Made in the USA. 90 day warranty