Give a gift a day right up to the holiday with the action-packed fun of “GraviTrax Advent Calendar” and set those marbles racing! This Christmas season, open the doors to 24 days of exciting GraviTrax surprises! Each compartment reveals a fun GraviTrax gift, from height tiles to tracks, from special curves to a spinner! Comes complete with 24 gifts and an extra surprise hidden within — everything you need to build a fun little marble run to race the 3 holiday-colored marbles! Makes an excellent introduction to GraviTrax, or a fun way to add additional pieces to an existing Starter-Set for repeat, year-round play! GraviTrax construction sets are a creative, expandable track system that challenges children to use their imagination to design their own marble runs! STEM-friendly concepts build critical thinking and problem-solving skills. Totally open-ended, every GraviTrax set has a boredom-busting variety of play options for hours of fascinating fun. Master the basics, then add expansion sets to build the tricked-out track of your dreams!