Help Botley™ set off some chain reactions with this interactive 40-piece accessory set. Set up STEM-inspired obstacle challenges filled with falling dominos, rolling balls, and swinging hammers, then code Botley to get things moving.This 40-piece set includes: Swinging hammer, Rotating gate, Ramp, Ball, Large domino, Medium domino, 30 small dominos, Specially designed detachable arms, and Activity Guide.