How is heroin typically packaged for sale?

Heroin is typically packaged for sale in plastic bags or balloons due to their convenience and effectiveness in securing the drug. These packaging methods help to protect the heroin from moisture and damage while making it easy to transport and conceal. Plastic bags provide a lightweight option that can be easily sealed, while balloons allow for discreetness and can be efficiently packed for individual sales.

The other options represent less common packaging methods for heroin, as they may not offer the same level of practicality or discretion. Glass vials, small boxes, and aluminum foil do not align with the standard practices observed in illicit drug distribution, where speed, stealth, and ease of use are paramount. Thus, the packaging choice of plastic bags or balloons is most reflective of the typical methods used in the drug trade.