Spread their lips and keep their mouth open and awaiting your pleasure. This loc king gag features a 1.5 in diameter opening at the front, the perfect size for a ccepting all sorts of objects... a rolling buckle at the back locks in place eas ily with the additional of a standard small size lock (not included) and is adju stable to fit most any size head. The tunnel gag extends slightly into the mouth , which keeps the teeth and tongue out of the way, leaving your sub no way to re sist anything you want to feed them. The gag is made of sturdy steel and genuine leather, for a high quality piece that is sure to last.