Draw a line and watch your Tracer robot follow it! Using optical sensors, Tracers will track the path of black lines drawn on white paper. Paper can be taped together, allowing for ever increasing and complex paths for your Tracer. As an added bonus we’ve included downloadable and printable “starter” paths for every beginner! Measuring approximately 2 3/8” x 1 3/4" x 3", each Tracer Robot is available in green and purple and requires 4 easily replaceable AG13 batteries, (included). Blaze your own unique trail with Tracers! Features & Benefits: Optical Sensors Follow Hand-Drawn Paths. Limitless Number of Paths & Designs. Improves Creativity, Drawing & Hand-Eye Coordination. Includes 1 Tracer Robot, 1 marker & 1 instruction manual. Available in Purple and Green. Tracer Robots Measure Approximately 2 3/8" x 1 3/4" x 3". Requires 4 AG13 batteries, (Included and installed).