The Clothes Pin™ works like an old fashioned wooden clothes pin to hold cover slips onto Real Crystal® IR cards. The spring action clip is opened simply by squeezing it between your thumb and forefinger like a clothes pin. The Real Crystal® IR card fits perfectly inside the clip. It has a clear aperture where the cover slip is clamped to allow the beam to pass through the optics. This holder slides into the universal slide mount found in all spectrophotometers.