With an assembly selected in a 3D scene, selecting this tool will merge geometry using the same material into a single geometry. In the image shown to the left, the three selected geometry in the car model are using the same material. In the right image the Merge.
Smooth Normals
this tool can be used to average the normals of the geometry to appear smoother during rendering
Flip Normals
Clicking this tool will have thw selected objects normals flipped.
Combine Vertices
Vertices having the position and normal direction will be replaced by a single vertex, using this tool. This will reduce the size and complexity of a 3D model.
Info
Clicking this tool will display Geometrical Info dialog, showing the number of Objects, Vertices, and Polygons in the selected geometry. Knowing the number of vertexes and polygons can help a user estimate the size of the output file. This might make the user ignore some details, for sharing efficiency.