Sandwich cells can be used to recondition sealed cells, to have backup or supplemental sealed cells of different pathlengths, or in a demountable cell. You will find sandwich cells that will fit most sealed and demountable cell holders that have been made in the last 25 years. The SL-3 configuration uses 38.5 x 19.5 x 4mm rectangular windows, the Beckman-Specac configuration uses 41 x 23 x 6mm rectangular windows and the SL-2 & Spectra-Tech configuration uses 32 x 3mm discs. These sandwich cells can be used with any sealed or demountable cell mount with the same window sizes, regardless of who may have manufactured the cell in the mount. They are compatible with Barnes, Beckman, Buck, Mc Carthy, Perkin-Elmer, Pike, Spectra-Tech, Specac, Wilks and Wilmad cells and mounts.