This specific 3D model, "M9 bayonet knife Low-poly 3D model shop", is an asset made available by "Unknown author".
Can be downloaded at "Unknown platform" by following the link.
Usage of this 3d asset is subject to the "Unknown license" agreement.
STL (Stereolithography, filesize: 362 KB), OBJ (OBJ, filesize: 673 KB), FBX (Autodesk FBX, filesize: 682 KB), PNG (PNG, filesize: 174 MB)