Flex mouthpieces are made using Stomvi's proprietary Bellflex brass alloy. This alloy has extremely resonant properties and is integral to the design of Flex mouthpieces.
The VR series use a new cup and backbore balance, designed by K.O. Skinsnes. VR cups are a hybrid design, functioning like a shallow cup in being easier to play and increasing endurance, yet with their unique shape and internal volume producing the bigger sound and timbre of a deeper cup, with a rich spectrum of harmonics in the sound.