Guardian One® for Dogs 20.1-25 Lbs Nitenpyram starts working within 30 minutes, while Lufenuron provides a 30-day protection.Nitenpyram and Lufenuron, both renowned in the pet supply industry, offer gentle and effective results with no preservatives or artificial flavors.Guardian prides itself on using all-natural, high-quality meats in their products, preserved with oak or hickory-fired smoke for long-lasting freshness.Our capsules are sealed tightly with a locking design to minimize air exposure, ensuring better preservation compared to standard tablets and chews.