BD40BD20 battery adapter converts for 40V lithium batteries to 20V lithium battery, use Compatible for 20 volt cordless power tools. Fully utilize 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 for 40V lithium batteries(BL4040, BL4025, BL4045, BL4045F etc.), Convert top Use for 20V cordless drill,Impact Driver,Brushless, chain saws, lights, blowers tools and other outdoor tool. Safe & Reliable: convert adapter built-in voltage protection chip, made of high quality ABS plastic, safe and . 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' be used for power charging, this adapter not fit into any chargers.(Please remove the adapter before charging battery). Color: Black Material: ABS Package Contents: 1* Battery Adapter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.