Breville Single Dose Hopper with Bellow – Reduce Retention & Maximize Freshness The single dose hopper bellow upgrade is designed for home baristas to allow you to single dose with the Breville espresso machines. Single dosing is the process of weighing and adding the exact amount of coffee for one coffee shot. This innovative accessory sits in between the existing hopper and the lid allowing you to create a vacuum in the grinding unit to displace any trapped coffee grounds. The integrated bellow system ensures minimal grind retention by pushing out trapped coffee grounds, reducing waste, and maintaining flavor integrity. This hopper helps you achieve a cleaner, more precise dose every time with less waste and no more leftover means in the hopper to go stale.