What is a heroin finger?

A heroin finger, or finger of heroin, is typically used as slang for an amount of heroin. While a finger is not an exact estimate, it is typically 5 to 7 grams. The term comes from tearing the finger off of a disposable rubber glove and filling it with heroin. The open end of the glove is then tied shut. Rubber balloons are also used. The benefit of a finger for a dealer is that they are not selling a set measurement so they can value the heroin much higher than what it might actually be worth.