They were from Amazon but appear to be out of stock. I’ve been using them for about two years and they are great.

Fermenting Caps Kit with Fermentation Airlocks, Stoppers & Wide Mouth Pour and Store Lids - Mold Free Preserving & Pickling - Make Your Own Pickles, Sauerkraut & More with Earth-Kind Kits https://www.amazon.com/dp/B017GFUDWQ/ref=cm_sw_r_cp_api_WKtvBbXZ5XSFM