Each Osmo kit includes a base for your tablet (iPad or Amazon Fire) and a red reflector for the camera, in addition to the game pieces that you need to play with the Osmo apps.
Here's more information about Osmo Starter Kits.
Please make sure your device is on this list of Osmo-compatible devices.
All of the Osmo apps are available to download (or update) from the iTunes and Amazon App Stores.