Freshness, quality and effectiveness are guaranteed ! Natural urines come from whitetail deer at the Buck Expert research center. They are fed with the same diet as wild whitetail. For maximum results, use natural urine at your salt licks, bait sites, while still hunting and while calling. Also a great tool to use to stop a deer in an opening you are watching from your stand. It is recommended to keep the urines between 33 °f and 41 °f.