Drips during the daytime hours and shuts down at night. A scrap- dripper hung over a natural or mock scrape is the surest way to really heat it up and get that buck to hang around.It has no valves or moving parts to cause problems. Absolutely trouble-free in cold weather and operates from 2-3 weeks on 4 oz. of scent. It is the change in temperature from night to day that operates it.