Hey Byrd. It works in reverse than ayringe. As you depress the plunger it creates a high millibar suction so it draws out the venom rather than injecting something. They come with a variety of cups and easy to use. Last I saw them was sporting goods at wal-mart. well worth the investment if you have allergies insect venom or get a snake bite. The old cut and suck methods were dangerous, nerve damage and infection just two of the potential problems.