Theatrical flash powder is flash powder commercially manufactured in premeasured kits not exceeding 1 ounce in weight, and mixed immediately prior to use and intended for use in events such as theatrical shows, stage plays, band concerts, magic acts, thrill shows, and clown acts in circuses. A manufacturer’s license allows on-site manufacturers to operate nationally on one license issued to their principal place of business.

[27 CFR 555.11: definitions of "flash powder" and "theatrical flash powder", 555.41(b)]