Unlock hidden pathways and mysterious marble routes with the GraviTrax Expansion Tunnels set. This essential add-on transforms your GraviTrax Marble Run System with 18 innovative components that conceal your marble's journey, creating suspense and surprise at every turn. Navigate between different height levels and switch directions while keeping spectators guessing where your marble will emerge next. Perfect for builders seeking to elevate track complexity and add an element of unpredictability to their designs. Compatible with all GraviTrax Starter Sets, these tunnel pieces are your gateway to endless creative possibilities and captivating marble-run experiences.