Ryobi's regular 40V batteries are designed for use ... but it appears that the batteries are entirely interchangeable. This means you should be able to use your old 40V tools with the new 40V ...

Unfortunately, it's not perfect, as not all tools and batteries are interchangeable. For example, if you have a 40-volt Ryobi ...

That should not come entirely as a surprise to ONE+ fans, as Ryobi cleverly conceived the entire lineup to feature interchangeable ... ranges of ONE+ batteries in the 18V and 40V variety, and ...