These 'bruise pants' are designed to fix that problem, by giving the athlete a visual indication of just how badly they may have been injured. The custom-fitted pants have small pockets in several vital areas, where you can slip in a special pressure-sensitive plastic film insert loaded with colored dye. When the film is sharply impacted, the magenta dye rises to the surface to show where the athlete was struck. The size and darkness of the discoloration also gives an indication of just how hard the blow was.