This ARRI Conversion Kit AS18 to M18 allows you to convert your Arrisun 18 lamphead (a lamphead that uses common ARRI spread lenses and a PAR reflector along with spot, medium and flood focus settings for an intense, efficient light) to an M18 lamphead (an open-face, lensless fixture with a beam angle of 20° to 60° with a wide usable field angle that combines the characteristics of a PAR and a Fresnel to create diverging rays of light). Both fixtures are designed to accept a new power class of lamp--the 1800 SE HMI lamp--that can operate on a 20A household circuit.