What is the name of the Technic pieces that snap together to make a track? We have these little black Technic pieces that connect together; they make a track that fits over the gears (sort of like wheeled-belt-track on excavators or tank track).

Can you tell me the name of these pieces? The kids love them, I'm hoping to buy more in the Pick a Brick.
There are three types of chain/track that are similar to what you describe, none of which are currently available through the official Pick A Brick, though all are fairly common on BrickLink.


The smallest is the Technic, Link Chain
The medium sized is the Technic, Link Tread
The largest is the Technic, Link Tread Wide with Two Pin Holes


There are also several belt styled tracks that might fit your description, but it sounded more like you were referring to the modular parts.