This is a great set of four 3.5" straight wooden track pieces perfect for adding on to your current Conductor Carl train set. These are four interlocking pieces of track. They are not only compatible with your Conductor Carl but also your Thomas the Train engines and cars. These four pack add on packs come in four different styles: 6" straight, 6" curved, 3.5" straight, and 3.5" curved. Grab one of each for the ultimate toy train fun!