The VE-VE Single Pair Assembly has 4 Wobble rollers per pair for adding more hull support to your boat trailer. Mounts to cross members up to 3" x 5". The 2-1/2" sq. tube is 14 ga. Roller assemblies (2 ea. wobble rollers on shaft) have an outside to outside width of 14". The distance from top of trailer frame to top of the rollers is 7-5/8" on the lower adjustment and 8-3/4" at the top adjustment. Packaged one pair per carton with all mounting hardware.