With four exciting sounds when trains travel through, this is more an adventure park ride than a tunnel. Welcome additions to any wooden railway. The more you add, the more you enjoy. Hear 4 exciting sounds when trains travel through. Can also be activated by hand. Requires 2 x AA 1.5 V batteries (not included). Connects to all BRIO trains and the BRIO wooden railway system. Brio trains and tracks work with Thomas, Melissa & Doug, Nuchi, and all other major train brands.