The Westcott Optical Spot by Lindsay Adler Color Correction Gel pack is an add-on accessory for the Westcott Optical Spot. This gel pack can be used with most flash heads up to 100W to make fine color adjustments. Colors included are Full CTB, 1/2 CTB, and 1/4 CTB (blue color correction), Full CTO, 1/2 CTO, 1/4 CTO, and 1/8 CTO (orange color correction), Plus Green, 1/2 Plus Green, and 1/4 Plus Green (green color correction).