I bought from Moss, and it was a very nice seal, molded to the shape of the frame. I learned there was no way I was going to "pull" it through, though. I wound up started in the middle, hooking in the front edge and stuffing the rear with a smooth tipped screw driver. It took a good hour to finish it.
My last seal was from TRF, and it slid in with no problem. It was not molded to shape. I like looking at the Moss seal. I like installing the TRF seal!?!