HELP - where to source a matching brick moulding product for re-siding house? Ran out mid-project.

Hoping we can get some help here. We started off re-siding our house with a brick moulding-type PVC product that FIL sourced for us through craigslist. Sure enough, we're short by 8 feet of product.

Anyone know how we could go about finding a match? Or the real name of the material? Anything that would help us search or source it. Link to imgur album of the product. The little rounded piece isn't visible so that doesn't need to match, but the angled cut does show.