ATC via Amazon offers the Masione P108 18-volt Lithium-Ion Battery for Ryobi One+ for $45.99. Coupon code "B4EIK8V6" cuts it to $37.99. Plus, Prime members grab free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.15.) That's the lowest total price we could find by $6. It's compatible with all Ryobi 18-volt One+ tools. Deal ends October 16.