Size Unknown but most likely a xl lightweight alluminum buckle (1000lb proof-load test) on dog shoulder position which the most load bearing point when dog is pulling. stitching by Bartack and X in box pattern on each joint and load bearing point, dog will not break/snap off the harness. Durable handle is sewn tough and large enough to grab the harness quickly and easily. Double leash clip D-ring, one sewn on the back near the neck for normal walking, another sewn on the front for no pull.