Plug-in used by 3ds Max, a program used for creating and animating 3D models; contains a utility for the software, such as a file format importer or exporter; may be a Standard MAX plug-in included with the software, or an Additional MAX plug-in added to the software; used for extending 3ds Max with new capabilities.

DLU plug-ins can be viewed in 3ds Max by selecting Customize → Plug-in Manager.... Standard MAX plug-ins are located in the \stdplugs\ directory of a 3ds Max installation, while Additional MAX plug-ins are stored in the \PlugIns\ directory. Some examples of Standard MAX plug-ins include: FBXMAX.DLU: .FBX File Importer/Exporter POLYGONCOUNT.DLU: Polygon Count Utility BATCHRENDERUTIL.DLU: Batch Render Manager CBROWSER.DLU: Asset Browser Utility CURVECONTROL.DLU: Custom Curve Control tool