GreenWorks 20202 G-MAX 40V Li-Ion 12-Inch Cordless Chainsaw, (1) 4AH Battery and a Charger Inc. G-MAX 40V Li-Ion Battery System powers multiple tools for complete yard system--includes 4ah Battery and Charger 12-Inch Oregon bar and chain, perfect for cutting branches and limbs with ease Tool less chain e=tensioning for quick adjustments so you can get back to the task at hand Automatic oiler applies oil to the bar and chain to ensure durability and extend the life of the chain Translucent oil tank for clear view of oil level 40-volt, 4.0 amp hour lithium ion battery provides more power and longer run time Auto oiler with clear view window for easy oil level check Tool less chain tensioning