A fancy tea ball that has a miniature "croissant" made out of a metallic resin attached to the end of its chain. Because it is made of stainless steel, it will be appropriate for the brewing of any and all varieties of tea.
Put the tea into the ball, place the ball into your cup, add the water, let it steep for as long as you like, and then remove the ball once the tea has reached the desired strength for you.