One of the biggest appeals of the upcoming RED Hydrogen One phone (other than the holographic screen) are the pogo pins on the back that will let the phone serve as a central hub for accessories, including RED’s signature cameras. Today, RED announced a partnership with camera company Lucid, and now we know what the first of these accessories will look like: a hulking black box with two hardware-synced 4K cameras.

The as-yet-unnamed accessory leverages Lucid’s existing work in shooting 3D and VR content along with the company’s “3D Fusion Technology” to stitch together the two 4K streams to create traditional 3D video. It’ll also be able to make content in RED’s 4V format that can be displayed on the Hydrogen One’s unique screen to create a 3D effect. As for the Hydrogen One itself, it slots into the new camera to serve as a 3D viewfinder for the setup.

The Hydrogen One’s accessories concept isn’t new — Moto phones have had several mods and Essential offered a few add-ons at launch — but attaching your phone to a high-end camera is unlike anything smartphones have been able to do before. It’s also going to be costly; RED says the preorder price for the Hydrogen One is $1,195.

There’s no word yet on a price or release date for the camera attachment, although we do know that it will be sold through RED. Presumably, the accessory will launch sometime near or after the phone goes on sale later this summer.