Sealock is a dry bag manufacturer and OEM supplier building in both TPU and PVC. The useful question in this comparison is not which material is better in the abstract — it's which performs better under the conditions a dry bag actually faces: rolled and unrolled several times a day, dragged across rock, left in a hot boat, packed away creased for a season, and expected to seal on the first attempt with cold hands. That framing gives clearer answers than a generic spec sheet, and it changes which material wins depending on the product.