Interesting, now the site is closed, I cannot confirm, but I was sure the picture on Glendale Junction was of the Hillman bridge clamps, with the spring loaded ball bearing.
This picture clearly shows the spring loaded ball bearing. In my communication I was told that these were Genuine Hillman bridge clamps.
In any case, if what was sold was just a solid screw, that would explain why some people had issues, they don't work worth a darn without the "spring" that snaps the rail in place.
Greg