If you like watersports, you should take a look at this maouth gag with funnel.
This sturdy harness is made of 20mm wide and 3mm thick rubber, and fits perfect.
Outside is an attached large rubber funnel, inside a hollow penis shaped mouth gag.
Optional the back buckle can be equipped for locking with a padlock.
The harness fits for a mouth height circumference of 40cm to 60cm.
The shown mask is not included.