KATSU FIT-BAT Cordless Tools Range they all take the same battery, works on both 18V or 21V, compatible with LXT range, use your current or easy to find on amazon (compatible with BL1850 BL1860B BL1855 BL1840 BL1830 LXT-400 BL1820B BL1815)
With brushless motor the battery lasts almost twice longer than normal brushed motors, in addition it is maintenance free
41mm max cutting capacity with a compact design
10800r/min high no-load speed delivers smooth cut
Idea for wood, soft metal, tile, plastic and other DIY projects around the house