Appropriate for Grades K-12 Maybe we should call this product "teacher developed, bat tested" because teacher-developer Ralph Fudge reports that shortly after he hung the prototype in his yard, the first bat moved in. In fact, this wooden structure features two compartments to house a total of approximately 100 small bats (which makes the self-cleaning design a really practical feature!). The structure meets BCI (Bat Conservation International) standards. Dimensions: Bat House: 37cm x 22cm x 5cm Inner Compartments: 30cm x 18cm Includes: fully constructed bat house and background information.