Floor display contains 12 ThermaCELL mosquito repellent units and 18 refills. The unit operates using a butane cartridge which is used to heat the repellent mat which in turn releases the repellent into the air. It is odor free and repels mosquitoes, black flies and others. Each unit will work up to 12 hours, 4 hours per mat. It will provide 225 sq. ft. of protection. Refills are sold in packs of 24. Order # 23192.