These enclosed trailer screws have an FX2 coating that far out lasts zinc coatings and others on the market.
They are able to withstand 1248 hours in a salt spray test.
Original trailer screws are usually #10x3/4" but these screws are #11X3/4" which is slightly larger and will enable a tighter fit when going into the original hole.
A #2 square bit is needed to drive the screws or you can purchace the double square bits that I have on my site, and the screws are self drilling.
Instead of upgrading to a new trailer when the screws are rusty and corroded just replace them with these screws at just over 6 cents per screw. I also carry 1 inch screws
Check them out at my website: www.straightlineinnovations.com