This is the Zoot AERO VG wheel, which has a larger bore to accept the purpose made VG boss (see separate item).
This very clever 2-piece design clips on and off a standard round base bar. Designed for the pilot who doesn't have to use wheels, but likes to do so as a means of protecting the uprights! Priced and sold singly, but you will need two wheels, of course! See separate entries for the normal Aero wheel and for the VG boss.