This is an adapter for the Molten Digi Timer Challenge that runs on 4 AA batteries. This is a set that starts with 4 AA batteries. It lasts for about 8 hours or more with rechargeable batteries (since they are rechargeable, it is expected to last even longer with alkaline batteries.) The main unit is not included. Only the set indicated by the red arrow is for sale. 【Manufacturer】 molten Molten 【Product Name】 Digi Timer Challenge 【Model Number】 UD0010