The FYI Sewer System, AKA #FYISewerSystem when searching Marketplace, is a series of builder's kits consisting of rooms, entrances, tunnels, and various other structures you can use to connect together to make your own sewers, bunkers, or whatever you can imagine with the included builder's kits.
Simply mix and match your favorite tunnel kits with rooms and entrances. The connections are designed to line up properly and make building a breeze! You can create your own awesome sewers, bunkers, military bases, etc.
The PBR Cave System uses PBR rendering with fall back legacy textures. It requires a viewer version 7 or greater that supports PBR. It has advanced lighting and materials and you do not have to worry about textures and baked lighting making connecting pieces a challenge.
PBR is the future, it no longer requires different baked color versions as separate products, you can usually edit the lighting yourse