Inside each Kit: Four-stage filtration kit includes a H13 filter, medium filter, customized germ reduction filter and activated carbon filter. Recommended Use: Replace once (1) a year under normal conditions, or more often under harsher air quality conditions to maintain efficiency. Approximate Dimensions: 18.3 x 16.4 x 4.6 inches. Recommended Use: Replace once (1) a year under normal conditions, or more often under harsher air quality conditions to maintain efficiency. Approximate Dimensions: 18.3 x 16.4 x 4.6 inches. Filter-Monster branded H13 replacement compatible with Rabbit Air MinusA2 filters remove smoke, dust, pollen, pet dander, mold spores, and dust mites from the air.