 Great American Market (GAM) offers a special effects unit, the SX4, that is mounted inside a Source Four in a similar manner to the Seachanger Color Engine and offers a large selection of drop-in accessories that range from gobo-changers to overlapping looping gobos.Several manufacturers of HMI sources, such as Kobold, provide lighting fixtures that provide "daylight balanced" light through the Source 4 without the use of gels.This is accomplished by replacing the lamp assembly on the back of the Source 4 with an HMI lamp head.