Magnetic holders are convenient for holding KBr pellets or thin polymer films. They are also useful for mounting a 13mm crystal that has been used as a microscope slide in a standard spectrophotometer sample compartment. The film sample, pellet or optic is held in place by a magnetized rubber plate. These holders fit the universal 2" x 3" slide mount in all spectrophotometers. Use of paper inserts facilitates mounting small samples.