Flexibility of the bubble

I can not find the manufacturer of my casement windows on any part of the window so I can't go to a particular site and buy what I need. I removed the old bubble seal which was existent but the bubble part was split down the length of the bubble. The measurements for 58-053 are correct but my question is this. Is the bubble part of the seal (58-053)really thin and flexible? I tried some bubble seal from my local hardware but the rubber was too thick and the bubble would not compress enough for me to shut the window. The bubble part needs to be very thin and flexible. Thanks.