Pup out or sub out. Heavy, solid 304 stainless steel collar with four D-rings welded on. Perfect for play, because you know, attachment points! Collar closes via hinge mechanism. Where the collar closes are two holes. One of the holes is perfectly placed for a tag, the other hole is used for a lock. A pin and small brass padlock with 3 keys are included. The pin can be removed and a larger lock can be used if desired. Inside diameter measures 5-1/4”, almost 7/8” thick. Weighs 1lb 1oz.