"Second, Jacobson argues, as have others, that colors are in limited supply. See, e.g., NutraSweet Co., 917 F.2d, at 1028; Campbell Soup Co. v. Armour & Co., 175 F.2d 795, 798 (CA3 1949). Jacobson claims that, if one of many competitors can appropriate a particular color for use as a trademark, and each competitor then tries to do the same, the supply of colors will soon be depleted. Put in its strongest form, this argument would concede that ”hundreds of color pigments are manufactured and thousands of colors can be obtained by mixing.” L. Cheskin, Colors: What They Can Do For You 47 (1947). But, it would add that, in the context of a particular product, only some colors are usable. By the time one discards colors that, say, for reasons of customer appeal, are not usable, and adds the shades that competitors cannot use lest they risk infringing a similar, registered shade, then one is left with only a handful of possible colors. And, under these circumstances, to permit one, or a few, producers to use colors as trademarks will “deplete” the supply of usable colors to the point where a competitor’s inability to find a suitable color will put that competitor at a significant disadvantage. This argument is unpersuasive, however, largely because it relies on an occasional problem to justify a blanket prohibition. When a color serves as a mark, normally alternative colors will likely be available for similar use by others. See, e.g., Owens-Corning, 774 F.2d, at 1121 (pink insulation). Moreover, if that is not so – if a “color depletion” or “color scarcity” problem does arise – the trademark doctrine of “functionality” normally would seem available to prevent the anticompetitive consequences that Jacobson’s argument posits, thereby minimizing that argument’s practical force. The functionality doctrine, as we have said, forbids the use of a product’s feature as a trademark where doing so will put a competitor at a significant disadvantage because the feature is “essential to the use or purpose of the article” or “affects its cost or quality.” Inwood Laboratories, Inc., 456 U.S., at 850, n. 10, 102 S.Ct., at 2186, n. 10. The functionality doctrine thus protects competitors against a disadvantage (unrelated to recognition or reputation) that trademark protection might otherwise impose, namely their inability reasonably to replicate important non-reputation-related product features. For example, this Court has written that competitors might be free to copy the color of a medical pill where that color serves to identify the kind of medication (e.g., a type of blood medicine) in addition to its source. See id., at 853, 858, n. 20, 102 S.Ct., at 2188, 2190, n. 20 (”Some patients commingle medications in a container and rely on color to differentiate one from another”); see also J. Ginsburg, D. Goldberg, & A. Greenbaum, Trademark and Unfair Competition Law 194-195 (1991) (noting that drug color cases “have more to do with public health policy” regarding generic drug substitution “than with trademark law”)."