Bottom weatherstrip to a Certainteed double hung vinyl window

Thanks for posting. We may be able to help, but Certainteed windows use a lot of different types of weatherseal--the good news here is that some generic types might work perfectly as replacements. Can you show us the 'end profile' of the weatherstripping in question? That cross-section view is the best way to identify a replacement. We'll do our best to assist you from there.