Digital Theory by ETron Circuit Labs is Electronic Education Curriculum designed for the 21st century student. Featuring 35 exciting Labs, Digital Theory picks up where The Basics leaves off teaching the necessary Digital Theory needed to be competitive in a technology based job market. Digital Theory is fully backwards compatible with Tron.ix 2 and Mr. Circuit 2/Digital Magic courses. This is for the Replacement Parts Only. DOES NOT INCLUDE THE MANUAL, BATTERY, OR SOLDERLESS CIRCUIT BOARD