About this item Function: BD40BD20 battery adapter converts for Black and Decker 40V lithium batteries to for Dewalt 20V max lithium battery, use Compatible for Dewalt 20volt cordless power tools. Fully utilize various high-capacity batteries for longer and more convenient use of Cordless power tool,relax outdoor and indoor working anytime. Superior Compatibility: This battery adapter convert buttom compatible with Black and Decker 40V lithium batteries(BL4040, BL4025, BL4045, BL4045F etc.), Convert top Use for Dewalt 20V cordless drill,Impact Driver,Brushless, chain saws, lights, blowers tools and other outdoor tool. Safe & Reliable: convert adapter built-in voltage protection chip, comply with FCC RoHS and CE security testing standards, made of high quality ABS plastic, safe and durable. Easy to Install: This adapter is designed to compatible with 20V tools,much easier to remove than original adapters,fits well and work great. An Adapter Not A Battery: This can compatible with 20V battery adapter, Converter can't be used for power tool battery charging, this adapter will not fit into any chargers.(Please remove the adapter before charging battery).