Kit for small and medium aquariums: Inner dimensions: 9.65 cm (H) x 6.35 cm (D). Outer dimensions: 12.95 cm (H) x 8.13 cm (D). Suitable for medium aquariums shorter than 58 cm. Perfect for bettas, shrimp, guppies, clownfish, platies, and other aquatic animals. Practical breeding box: Two separate compartments provide a completely safe environment for breeding parent fish and raising fry. Effectively protects fry from attacks and predation, improving their survival. Unique mesh design: The large-mesh plastic net allows fry to easily fall into the protected area below. The fine-mesh nylon net at the bottom ensures good water circulation while keeping inhabitants safe. Versatile: Also functions as a divider! In addition to being an incubator, this fish breeding box for aquariums helps keep aggressive fish away and provides a safe refuge for weak or injured fish. You can also isolate them inside to tame them. FLOATING DESIGN: No suction cup needed! Two weightless foam rings allow the plastic isolation box to float on the water at all times. The depth of the two boxes in the water can be adjusted as desired by moving the foam rings up and down.