3D image format used by SolidWorks CAD software; contains a 3D object or "part" that may be combined with other parts into a single assembly (.SLDASM) file.
Program(s) that open sldprt files
Windows: Solid Concepts SolidWorks or SolidWorks Viewer; Adobe Acrobat 3D
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/sldprt