This is a high-quality pre-formed shower system. There is a shower pan base and a corner wall unit that sits on top. Both pieces have flanges that you seal with a bead of sealant and then bolt the two pieces together. Once installed, it will never need caulking to maintain it. It is in new condition - I took it out of the carton but never installed it. Asking price is less than half of what I paid for it.
Here is a link to the vendor's site I bought it from (same model, different color, the one I have for sale is white):
https://www.oasisshowroom.com/Locations-throughout-Pennsylvania-and-Delaware/Aker-141047-000-006-Sterling-Silver-Shower-System.HTM
Here is a link to the manufacturer's site (this shows the color of the one I have for sale):
https://akerbymaax.com/product/kd-nas-acrylx-corner-two-piece-shower/141047/141047-000-002
Both sites will have specifications and links to installation guides, etc. I have printed copies of these to go with the shower unit.