Good add on if you use your Cauldryn on the go but with 2 small gripes.
it is no where near as easy to get this unit on and off as the battery and can be a pain. The other thing is the threading of the lid is so that the spot you drink from is on the opposite side of the cup and when you add the cord you will be turning it all the time to drink or check temp.
The one thing I did like is that it supercharges the heating element compared to the battery or home base so you get your water to 200 quicker.
Works as described. Boils water fast and keeps it hot. Great for camping. Tea and coffee in minutes without a stove. I save money not having to buy over priced coffee when traveling on the road! I liked it so much I purchased a second one to keep in my car.