Plunger-type cell mixers are fabricated from clear acrylic plastic. These mixers have been designed to aid the user when adding enzymes and other materials to solutions in cells. The spectrophotometer cell mixers feature 9.2mm x 9.2mm square plunger ends for standard 10mm pathlength cuvettes and 9.2mm x 3.5mm rectangular plunger ends for semi-micro cuvette style spectrophotometer cells.