TakaraTomy released capsule figurines for the second movie, and re-released them for the third movie... which showed up here through their international division Tomy.
Looks like new capsule figurines are being released for the fourth movie, which could show up here again.
A set of six - 5 Autobots and just one Decepticon.

- Optimus Prime, Bumblebee, Grimlock, Crosshairs, Drift
- Lockdown

They are 4cm tall, and each is a different colour, and as noted in the title, they look like they could be used as keychains, or as necklace (they have a beaded chain at the top, not a keyring)