what the hell is a sure grip

I was at a local glass shop on Friday and the old seasoned gray-bearded owner sees my Dart out in the parking lot and just for fun tells me the part number I'd find in the lower passenger side corner of the glass. Of course I had to go check and of course he was 100% correct. We told him about the '74 Satellite my son is building and he told us the number we'd find on that one as well. I'm not going to knock the young guys at all but I sure love those old timers who know their parts, can't beat them!