Robert Axle Project’s M12x1.25 adapter for Kid Trailers and Cargo Trailers are designed specifically to fit your Rad Power bike or Mahle/EBIKEMOTION Equipped E-Bikes. and allow attachment of any hitch-mounted trailer. These Hitch Adapters fit any trailer that has two wheels and a single point of attachment to the axle. This includes all the two-wheeled child, pet and cargo trailers such as: Thule, Chariot, Burley, Instep, Carry Freedom, and many more.