Small Particle Reagent (SPR) is a suspension of fine molybdenum disulfide particles in a surface-active solution for light-colored surfaces and a white suspension for dark-colored surfaces. It adheres to the fatty constituents of latent fingerprints to form a gray or white deposit – depending on the reagent, and is a quick and simple latent print development process (recommended by the U.K. Home Office, Scientific ReSearch and Development Branch). Each kit includes complete instructions.