The "5500-4200K CTC kit for Ext. 600/Compact," P/N 91611036, is an accessory kit for the Exterior 600 and Exterior 600 Compact that corrects the color temperature of these products to improve color matching with the Exterior 200.
The kit contains a 74 mm square, 56 Mired CTC filter; filter holder, screws, and installation note. Installation involves removing the front cover and lens, and drilling 3.5 mm holes in the effect module plate.
For the best color matching results, use either the MSD or HSR 575 lamp in the Ext. 600.