Kato Unitrack is a great solution to building your layout. You can connect and disconnect track sections easily to fit your needs or whims. But sometimes the track length isn't exactly a correct fit when working with different pieces and switches. That is where these expansion track pieces come in and save the day! I have used several to solve connecting problems. Another benefit is the plastic piece on the expansion section also serves as a retailer. I highly recommend these to anyone building a layout, particularly if you are running into problems fitting lengths of track together.