I buy silicone inserts from various sellers on eBay. They have generally come from Malaysia. They fit my OEM blades as well as aftermarket. There are at least a couple different "spine widths" (i.e. 6mm and 8mm) to choose from. I've had a pair in my OEM Mazda blades for about three years so far and they still work quite well. I pay about $8 for a pair of inserts.