"The container is far too small for even one crab, gravel is not an appropriate substrate for hermit crabs, the "ventilation" will likely make it impossible to maintain a proper level of humidity and someone mentioned that the hidey is made of cardboard so pretty much useless.
On top of this, there are so many things missing including gauges for heat and humidity, two bowls for water (one for dechlorinated, one for salt) and a food dish, a proper place to hide away, etc.
This should only be considered if in desperate need of a travel carrier for a short period of time, otherwise it is not worth your money."