On the other side of the spectrum, illicit manufacturers—frequently operating on unregulated international e-commerce platforms—use terms like "keychain," "toy," or "solvent trap" to sneak real, fully functional conversion parts past customs and law enforcement. These parts are often poorly disguised, sometimes arriving attached to a simple metal keyring to justify the "keychain" listing title.

The marketing pitch usually goes something like this: "It’s just a paperweight. It’s just a keychain. It doesn’t work. Don’t be a felon."

A is a small, specialized metal component designed to be inserted into the receiver of a semi-automatic rifle—most commonly the AR-15 platform—to enable fully automatic fire.