Extends the Class V (2-1/2") hitch box up to 48". Use with truck campers that extend beyond truck bed. Has 2-1/2" outside dimension at the hitch and 2" dimension at the end. 99-6435 extends 34" (4,500 lb. WC /6,000 lb. WD) and can be cut down to 24". 99-4518 extends 48" (4,000 lb. WC/6,000 lb. WD) and can be cut down to 41" (5,000 lb. WC/7,500 lb. WD).