When the original Vamo came out, some of manufacturers called it a "Bamboo," this isn't it.
This is what I called a "semi-variable voltage" in that it has 4 setting choices: green light(3.5V); yellow light(3.7V); red light(3.9V); blue light(4.2V), but not the same range as a Twist or Spinner (3.2v to 4.8v) and it can't be set to anything besides the 4 options.
The reason I asked about back-up is because it's cute and inexpensive, but it's basically a cheap device from China. Who know what the quality will be? If you have a reliable set-up in the same class, like a JoyeTech Twist, Vision Spinner, iTaste vv, etc. it might be fun to play with.
ETA: Or if you want to go more advances than that, there are the ZMax, Vamo, SVD and similar devices.