The mousquetaire is a feature which can be added to a long evening glove. It is an opening on the inside of the wrist fastened by three little buttons which allow you to remove your hand from the glove whilst leaving the sleeve of the glove on the arm. This is how ladies used to wear gloves while dining. They would put their hands back into the gloves only after the meal.
Gloves should be kept on when shaking hands, dancing, or presenting your hand to be kissed, but not when dining
Simply undo the buttons, gently tug the fingers of the glove off the hand and tuck neatly away. Practice will make perfect. Devilishly cunning and a godsend for those moments when a ring is being proffered or there is serious banqueting to be done.