From the release:
We have recently released our super new Tinnelon Pattern Tank Hull.
This obviously works great with our Tinnelon Turret, but is compatible with all our turrets.
There will be track units coming for this when they are done and we plan to release more hulls and motive systems over time.
Also, we are running a promotion on our Facebook page where people can win store credit for "Liking" our page. Once we hit each liker goal we will increase the credit, so everyone has multiple chances to win!