Description (copied from the manufacturer):

Clairol Pure White Creme Developer mixes easily with any Clairol Professional haircolor or lightener into a creamy consistency. Ideal for bowl-and-brush application. Provides a slightly thicker, more opaque mixture. Laboratory stabilized to guarantee consistent, predictable results. Designed for standard lightening action, superior gray coverage. For use with all Clairol Professional lighteners. Guaranteed fresh for three years.