Optimized for high speed fastening, the Milwaukee M12?,,? 1/4" Impact Driver? delivers unmatched fastening performance in a lightweight, tool belt portable design ? A high performance motor delivers 0-2,500 RPM for increased fastening speed. REDLITHIUM?,,? Battery Technology outperforms the competition, delivering up to 80% more run time. Additionally, an on-board battery fuel gauge displays remaining runtime.