21512 REESE TRI-BALL MOUNT (1-7/8", 2", 2-5/16") | Box opening of 2 in x 2 in. 200/2,000 TW/GTW capacity for 1-7/8 in ball hitches, 600/6,000 for 2 in and 1,000/10,000 for 2-5/16 in. Receiver Series 33, 35, 36, 37 and 44.