Polyrhythms Twisting Time Rhythm Theory & More-Progressive Drumming Essentials is a collection of material originally written for Modern Drummer magazine plus extensive additional content. This book breaks down fun and challenging material for progressive-minded drummers including double bass odd time signatures displacements odd subdivisions and modulations plus an in-depth section on polyrhythms and their applications to the drumset. Author Aaron Edgar is the drummer for the prog-metal band Third Ion. He's a regular instructor on Drumeo.com and a regular columnist for Modern Drummer magazine. He is known for teach advancedrhythmic concepts and has a knack for being able to break down and explain challening material in an easily understandable way.