Birchwood Casey Presto Blue - Presto Mag Gun Blue is a cold blue formulation that works on all steel (except stainless steel). Specifically formulated for when you want a deep blue luster on your firearms metal surfaces. For complete re-blue applications. Key Features: - Cold blue formulation that works on all steel (except stainless steel) - For complete re-blue applications Size: 3 fl oz, Comes with 2 absorbent pads. All backed by Westlake Market's quality product guarantee!