They were in stock and available for a few weeks, but I guess they’re popular again. We’ve been offering the protoshield for several years, but demand for these tends to fluctuate more than any of the other things we offer, so it’s difficult to predict.
A tip for finding our items on Amazon: only in-stock items can be found using the Amazon search bar. If an item is out of stock, Amazon will remove the listing from their search results and you’ll never find it by searching. However, you can always find the listing by clicking on the static URL for each item. For example, all of the Amazon listing are linked on the Mayfly’s main page and the accessory page: https://www.envirodiy.org/mayfly/hardware/accessories/
You can also use a search engine like Google to find any of our items on Amazon, even if they’re not currently in stock.