Milwaukee 48-11-1815N M18 18-Volt Compact Battery LITHIUM-ION battery delivers long life and run time with fade-free power Battery fuel gauge - Displays remaining run-time 18V Compact LITHIUM-ION. Equivalent run-time with 40% less weight than an 18V NiCad battery Milwaukee Digital Power Management. Overload Protection-Prevents user from damaging their cordless power tool investment in abusive situations Temperature Management System-Keeps battery in ideal temperature range to provide maximum life.