Where can I find the vinyl strip at the bottom of the bathtub?

I need to replace the vinyl strip at the bottom of our bathtub. It is the one which was installed by the contractor for all of our tubs. I have been to Lowe’s and Home Depot and the replacements which they offered were not the same. They have the tape which is sticky on the back but is far smaller that the original. We went to flooring but the only we found there was twice as large as what we have. Where do contractors get this stuff from?