A menthol capsule inside the filter of the cigarette. User squeezes the filter, capsule breaks, releasing menthol into the filter
Camel Crush is an R. J. Reynolds cigarette product that contains a capsule in the filter that, when crushed, releases a mentholated liquid that causes the smoke to be menthol flavored. When the tobacco smoke passes through this liquid-saturated filter, it gives it a menthol taste. The cigarette was released in the United States on August 25, 2008.
A similar technique is used in the L&M Forward, popular in the eastern European and Finnish markets. Technology Internet