The Arrowhead SPR Black is an aerosol-based fingerprinting product for the development of latent prints on wet, light, smooth non-porous surfaces. Earlier methods based on dispersed particles in aqueous solutions required the field mixing of powders, water and other ingredients to achieve similar results. The process was messy and cumbersome. Furthermore, the powder often created an ineffective mud-like liquid. As an investigative tool, SPR Black helps preserve and collect important evidence at the scene of the crime.