The new El Thunder Artist Collection Max 13 Edition 21700 supports 18650, 20700 and 21700 battery types.
The mod fits the hand nicely because the bottom cap has a bigger diameter and forms a waist and twisted notches are milled out for a better hand grip.
It’s very easy to switch between different battery sizes with the new El Thunder because the mod comes with perforated plastic cards that serve as an adapter for battery size. The plastic cards get fixed inside the tube using a special ridge. You can carry them around inside a wallet or a business card case. (While using 18650, you should attach the included magnet spacer.)
Great performance is ensured by the revised Collet Button System. It lowers transient resistance, cleans itself using friction, and makes every button press consistent regardless of where you press it. Contact area is also increased compared to the original El Thunder and El Thunder 20700.