During this season's 4 week vacation out west, I noticed that our threshold's two thicker stainless replacement screws both broke. Being that stainless is a softer metal, it is not a total surprise. I did hope that since they were thicker than the original screws, they would last forever. They did last 6 years. Unfortunately I can't find more of that same nice looking finish stainless screw. So I temporarily used hardened steel. Unfortunately they are hex-headed, not exactly a finished look, but at least they are low profile. Hardened steel will be stronger but might snap under stress as well, and would be very hard to drill out. I'll have to look around for even thicker stainless screws with nice finish heads resembling the ones that just broke.