Abstract: A connecting base for connecting an accessory to a vehicle includes: an attachment portion configured to be connected to the vehicle; and at least one post-receiving portion connected to the attachment portion. Each of the at least one post-receiving portion defines an opening configured to receive a post connected to the accessory. The opening is defined in an upper surface of the connecting base. Each of the at least one post-receiving portion includes: an inner peripheral surface defining the opening, the inner peripheral surface being shaped to be at least partially mated with an outer peripheral surface of the post; and a rib protruding from the inner peripheral surface, the rib being configured to engage a groove defined by the outer peripheral surface of the post. An accessory connector and an accessory system including the connecting base and the accessory connector are also contemplated.