Duracoat Ultimate Do It Yourself Firearms Finish - Can Only (OD Green) Aerosol Can of DuraCoat Firearm Finish in the color OD Green Can within a can technology allows release of hardener to mix and spray with no mess! Unique can-within-a-can technology provides the hardener right inside the can. Can is good for up to 4 weeks once activated No baking or pre-heating required