I had originally installed the OEM seal for the driver side axle, but after a month or two, it started leaking again. This is a somewhat big job, possibly damaging ball joints, and you most often need an alignment after, so I was not happy. Went online only to find out that this is a common occurrence with replacing the OEM with another OEM. Was told to go with Timkin. So I bought the recommended Timkin only to find it was the wrong size. Anyway, this National seal is metal around, with very good sealing properties. Time will tell, but it installed tight, and no leaks so far.