I also use small circular pinch hose clamps just to be sure they they stay on and provide a tight fit.
Note: check the sizes in the posted assortment.
When there is no supply from the usual RR sources, one must innovate and search for alternatives that work. Use Google and search accordingly. I'm sure there are OEM from other manufacturers that may work. Open the hood of your daily driver, a friends car, etc and you may notice a suitable replacement.