On March 2, 2011, vossner from East Texas, United States wrote:
Clever little gadget. It has a strip (paper?) which, when in contact w/ moisture, disappears from view. Once the plant is dry, strip dries as well and it now looks white. The back of the package has a limitied guideline for how deep to insert gauge, according to plant type. This is particularly useful for people who do not want to get their finger dirty by inserting in soil or for those who respond best to visual input.