Ryobi OP4026A Genuine OEM 40V High-Capacity Lithium Ion Battery w/ Onboard Fuel Gauge FUEL GAUGE: You can tell how much of a charge your battery has left, as well as any potential defects, with the onboard LED system WORKS WITH RYOBI OUTDOOR PRODUCTS: Over 15 tools in the Ryobi 40V line are compatible with these batteries, from string trimmers to lawnmowers COLD WEATHER PERFORMANCE: These batteries can function at temperatures as cold as -4 degrees Fahrenheit (-20 degrees Celsius) QUICK CHARGING: Get a full charge in as soon as 90 minutes when used with the Ryobi 40V Charger FADE-FREE POWER: This battery will not diminish in power as it loses charge, meaning you can work at full capacity until its power runs out