The Bontrager XXX & Pro Stem Blendr Duo Base can be used with both the Bontrager XXX & Bontrager Pro Stems. The Duo base allows for two Blendr accessory mounts so you can securely mount a light & computer or light & camera to your stem. Features Blendr works with this simple formula: Stem + Base + Mount. Add accessory. Bases for use with the XXX & Pro Stem Add any accessory mount (sold separately) for an elegant, integrated look