It's not one of the common profiles at all. The table is 3 piece slate, but the rails and everything else is particle board. Almost not worth the hassle. I think the sun had been hitting one of the rails, it's in a garage with a big sliding door, and the one closest to it is hardened up. They asked me to recover it anyway, so I did. Would maybe re-do the one rail if I could find a chunk of that rubber, but it's definitely not common. Only about 11/16ths wide, and only angles downward about 1/16th.
The closest thing I have found online is in this pic from a site in Taiwan, it's marked F