You can use an impact screwdriver without battery with a battery you already have in your toolbox. Slide your 18V Makita or Metabo battery on a matching bare tool and you can work completely cordlessly. This means you don't have to buy a complete set, which saves you money. One less battery also saves storage space in the shed or workshop. Make sure to check in advance whether your battery matches the brand, voltage, and battery platform of the impact screwdriver you have in mind.