Material: Food-grade silicone, BPA-free, EU- and FDA-certified. Country of Origin: Taiwan. Compatibility: O1 Brewer Steel RAW and Obsidian, O1 and O2 Brewer Tritan, older Orea porcelain and open-bottom glass drippers, Hario Switch base (with #8 regulator). How to use: 1. Choose the flow regulator (#2 or #4) based on the desired flow rate. 2. Attach it to the dripper’s spout. 3. Adjust the grind size and brew time based on the resulting cup.