This is a rail set that changes from a single track to a double track, curves 180 degrees, and then returns. You can connect four of your existing curved rails to make a complete loop. How about using it to expand your rails? ☺︎ The parts used are second-hand items that I received, so there are minor scratches and signs of use. Please understand that these are used items before purchasing. [Set Contents] Double track curved rail x 4 Double track straight rail x 2 Straight rail x 4 Single-track/double-track point rail LR x 1 each