I am a home DIY amateur. I have a Bosch PS50-2BL cordless 12v Oscillating Multi-tool, which I also purchased some time ago from CPO Bosch. It came with two older BAT411 batteries. I got the third one because there is room in the carrying case (an L-BOXX2 with a custom plastic insert) and I sometimes use this tool for long stretches. Actually, the batteries recharge pretty fast, but having the third one is nice. This one is slightly higher capacity than the older one. Shipping was quick. Doing business with CPO has been first rate.