The RYOBI 40-Volt Lithium Rapid Charger charges 3X times faster than the standard charger. Compatible with all RYOBI 40-Volt batteries. The indicator lights provide the battery charging status and even lets you know if the battery is too hot or too cold to charge. Spend less time charging batteries and more time getting yard work done. This charger can charge the included RYOBI 40-Volt 4 Ah High Capacity Battery in 40-minutes. This 4 Ah battery gets 2X more runtime than the RYOBI 40-Volt 2 Ah Compact Battery, while delivering the same fade-free power and performance. All RYOBI 40-Volt batteries come with an on-board fuel gauge to display remaining runtime. This battery works with most RYOBI 40-Volt tools and chargers. This kit is the perfect addition to your RYOBI 40V collection.