As we  know, Hangsen produced ECHO series e-cigarette, covering 3 model: ECHO, ECHO-E, ECHO-V.  They seems to be the same looking. But please note, theire components can not be mixed.

Difference as below:

1, ECHO comes with AUTO switch battery. and the battery lights on the tip. Echo-E and ECHO-V come with MANUAL switch battery. ECHO-E’s battery has light on the connection just like Joye ego. ECHO-V’s battery has light on the top just like normal auto battery.  AND THE MOST is they have DIFFERENT THREAD, so they have special cartomizer.

2, ECHO’s cartomizer’s Resistance is 2.4-2.7ohm it’s Capacity is 3.1ml.
     ECHO-E’s cartomizer’s Resistance is 2.6-3.2 ohm, it’s capacity is 2.3ml. Furthermore, ECHO-E cartomizer can fit normal ego kit, joyr ego and joye ego-tank
      ECHO-V’s cartomizer’s resitance is 2.4-2.8 ohm, it’s capacity is 2.7ml