Kills in hours. Kills non-stop for up to 12 months. No vapor, fumes, or odor. How Combat 12 Month 1 Works: 1. Roaches enter the bait station and eat the bait. 2. Roaches take the bait back to the nest. 3. Roaches share the bait, killing other roaches and destroying the nest. Guaranteed to work. Please recycle empty carton. Made in USA.