Chatter 2.0 is a duo-pack: one box contains two complete communicator kits, so you and a friend can build one each and message each other straight away.
In the box, per communicator:
Main circuit board, with the radio module built in
Acrylic casing
Battery holder and battery cover
Button caps and the plastic on-off cap
Metal bolts for the assembly
Guides. The box points you to three: a step-by-step build guide with over 100 photos, a usage guide, and a beginner-friendly coding guide. All of them live at circuitmess.com/blogs/resources. It is worth opening the build guide before you start, so you can see what the assembly involves and have everything to hand.
Plan on roughly two hours to build the pair. The recommended age is 9 and up — building involves handling small electronic components and following detailed instructions.
What the finished communicators can do is covered in CircuitMess Chatter 2.0 — Frequently Asked Questions.