Ans: Redlithium or Red Li-Ion is Milwaukee’s latest M18 (18v) lithium-ion battery. The red lithium technology gives more power with 20% higher torque and speed. The durability has also been enhanced which gives a 50% more recharge cycle and 40% longer run-time. Increased resistance to cold weather with 20% cooler operation down to 0ºF to -18ºC. Plus, comes with fade-free power with no memory effect.