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 UK Home Office, Scientific ReSearch and Development Branch) Each kit includes complete instructions