This stackable kit is designed for Raspberry Pi cluster users. This kit is exclusively for GeauxRobot Dog Bone case. You MUST have a Dog Bone case first (item B00MRKSGP2 or B00BR1IJUO). The kit works for all current Raspberry Pi's including 3B, 2 B, B+, A+, B and Pi A. You can build a stack case with your B+, B, and A on your original Dog Bone case. Please DO NOT purchase this kit unless you already have a Dog Bone case and a second pi. Dog Bone Stack Case guide: If you have N of Pies, you need one Dog Bone case and (N-1) stackable kits. N=the number of Pies you have. We also have 2-layer Dog Bone case and 4-layer Dog Bone case. Item B00NU70MZS and B00MYFAAPO.