A funnel gag consists of a funnel with a tube leading from its spout into the mouth, usually with straps to hold the tube in. Such a gag is used to force the bound person to drink a fluid. It is very easy to choke during such forced drinking. People involved with watersports may also find interest in this gag.
Look for a safe design that prevents choking. The funnel makes it easy for liquids to be fed into the submissive. Do not leave the submissive alone.