Milwaukee have drawn on their vast experience with grinders from back in the day with the American military and heavy industry. They have adapted the front end design and coupled it with the m18 battery technology to produce an outstanding range of grinders. M18 is the world's first battery platform to offer a complete range of grinders, from 4-1/2" to 9" all on the same battery. M18 FUEL™ is engineered for the most demanding tradesmen in the world. Delivering unrivaled performance in a compact structure, all M18 FUEL™ products feature three MILWAUKEE® exclusive innovations -- The POWERSTATE™ Brusless Motor, REDLITHIUM™ Battery Pack and REDLINK PLUS™ Intelligence Hardware and Software -- that deliver unmatched power, run-time and durability. Simply put, The MILWAUKEE® M18 FUEL™ line of cordless grinders deliver the best combination of power and run-time, all on the M18™ REDLITHIUM™ battery platform.