Bonide Bat Magic is not for sale in the following states: CA, DC, IN, KY, NM, WA, WI due to state restrictions or registration issues. Eliminating bats and cleaning up their guano can be difficult and dangerous, so for severe infestations or hard-to-treat areas, we would recommend contacting a local reputable professional company that specializes in these treatments.
Per the Bonide Bat Magic Product Label you will want to use one pack per 150 sq ft where the bats are present to try and push them from the area out of the home.
Bonide Bat Magic is for use in indoor areas only, such as in attics, wall voids, blinds, confined spaces, and chimneys. They cannot be hung outside as they would not be effective when exposed to the weather. The crack should be repaired if possible. You can hang a CD or other reflective object on the outside to help deter them from the area.
We do have a guide here that might help.