Gottsu produces the Double Ring and Master 2021 in metal. The Double Ring is based on the Otto Link Florida. The Gottsu Double Ring is an excellent mouthpiece. It sounds a little softer and more colorful than, for example, the Retro Revival Super D FL. I have been blowing the Gottsu Double Ring for two years and consider it one of the best replicas currently available! The Master 2021 is based on the Master Link from the forties: it sounds much darker than the Double Ring model. I have also been blowing the Master 2021 for about a year: I am very satisfied with this mouthpiece: I like it even better than the Double Ring because its sound is larger, rounder, more colorful and more complex. I prefer this sound. Both mouthpieces are highly recommended!