The ONA Polar Crystal Block is ideal for small areas such as closets, foyers, attics, cars, gym bags, boats, kitchens, garbage cans, cupboards or vents. Simply remove the cap, or punch several small holes in the cap and place in desired location. The ONA Block measures 3" x 3" and will fit in most places. The ONA Block will release its powerful agents and keep the location free from undesirable odors. Replace as necessary.