Lasts up to 90 days. Longest lasting air freshener for over 60 years! The K29 ScentStone is a high quality, long lasting air freshener made with the finest, safest, natural ingredients. It may be used: Under the seat of a car; In the home (bathrooms, closets, garage); At the office or any small space where air freshening is needed. K29.com. Made in the USA.