The Plant Pro-Tec Deer & Rabbit Repellent formula uses highly concentrated garlic oil to keep four-legged pests from damaging gardens, and a patented, long-lasting and easy-to-use delivery system that sets it apart from less effective spray-on repellents. Other repellents begin to break down when they come in contact with the air, and they require reapplication every two or three weeks, or more often if it rains. Unlike less effective options, Plant Pro-Tec’s unique biodegradable, patented delivery system releases the active ingredients slowly over time, keeping the odor strong and effective for between six to eight months, even if it rains. The active ingredient is contained in a biodegradable plastic container that lets the repelling vapors out, and also keeps air from getting in, which prevents oxidation. You simply break the seal to activate the unit, then clip the container directly to the plant, attach it to a nearby fence or lay it on the ground. Includes 250 units.