Alpine does not include a mounting cage with its Halo unit as the majority of Halo installations will typically require a model specific fitting kit when being installed into the dashboard/fascia of a modern vehicle.
This is Alpine's own Halo Specific Single DIN Cage that will allow you to mount the Alpine Halo9 unit into any traditional Single DIN aperture/fascia such as the factory fascia found in the post-2007 Defender 'Puma' dashboard.
