This Liposome-based repellent is the newest advancement in insect repellent technology. Similar to the earlier generation of polymer-based controlled release systems (like 3M® Ultrathon), the Liposome envelops the DEET and slowly time-releases it as needed, thereby extending the effectiveness of the repellent. Unlike polymers, however, liposomes are a natural compound which is more comfortable to the skin and easier to wear. The Liposome base enables the 30% DEET lotion to be non-greasy, with little to no odor. Ultra 30™ is also non-staining, resists perspiration, and is effective for up to 11 hours. Airline approved size.