Wodent Wheel SENIOR 11" DIAMETER W. SAFETY SHIELD/ASSEMBLED (DARK BLUE & BLUE)(TOTAL HEIGHT 12.3") 11" wodent wheel is only size with Safety Shield for added protection for pet paws and tail Wodent Wheels feature a unique design with a safe solid running surface and a support stand without dangerous pinch areas. The only exercise wheel recommended and approved by the ASPCA during their Seal of Approval program (1999-2006) Wodent Wheel Sr  11" diameter, 3.5" wide running track, 2.6" mouse-hole shaped entry holes. Overall height 12.3". Best for lady rats, squirrels, sugar gliders, Syrian or other large hamsters and small hedgies.