What paraphernalia is used for filtering heroin during preparation?

Cotton swabs are commonly used in the preparation of heroin for filtering impure substances or particulates from the solution before it is injected. They are effective at this task due to their fibrous texture, which can catch larger particles while allowing the liquid to pass through. This makes them a practical choice for users seeking to ensure a cleaner injection by removing contaminants that could pose health risks.

Others, such as tiny balloons, are typically associated with packaging drugs for transportation rather than the actual preparation process. Glass beakers and plastic filters may serve certain chemical or laboratory purposes but are not typically utilized in the immediate context of preparing heroin for personal use. Thus, cotton swabs are the most directly relevant paraphernalia for filtering heroin during its preparation.