Common accessory bought at your LBS or mail-order houses in the '70s-early 80s. With the advent of Kevlar belted tires and plastic 'tire liners', they went by the wayside. I still use them because they're cheap and effective. Over the years and 45,000 miles, I've replaced both the plastic tubing and the flicking 'wire' on mine. For wire I used a broken stainless spoke bent to the proper shape. Plastic tubing is plastic tubing...