Only try this with a partner that you fully trust.
Place the ring over the teeth and adjust the strap so that it fits comfortably but stays in place. Make sure that the ring diameter is comfortable as beginners may not like to keep the mouth open for extended periods.
Please take into consideration that your partner will be unable to communicate when the ring is in place. You should agree upon a gesture or series of gestures that clearly communicates the intent of your partner before diving into any sort of bondage play.
First time users need to consider that the O ring will make you drool as you cannot swallow properly when your mouth is forced open. Excess saliva will collect inside. Trying to swallow while being gagged is counterintuitive, futile and can interfere with breathing; best course of action is to try and relax.
Sanatized the O Ring thoroughly before and after usage in hot soapy water. Clean the ring, strap and buckle. Use a toothbrush to clean under the ring and buckle. Leave to air dry before string in a safe location.