i lose same surface i can't make a dimension of my object

same problem with .step format my file .3ds in this url : https://drive.google.com/open?id=0ByS1S3JyocwXRzFLRkQ0Ql9CcW8 i can't attach it here in emastercam , i can 't understand why

hello i have a problem with my file 3ds. i want to open this file with mastercam but without succes. i convert it in .stl and iges and open it with mastercam it s ok but my file lose lot of information and i have other forme and bad texture i want to ask your help how can i convert my file .3ds ans open it in mastercam with all qualities and first parameters . thanks you and for give me for my poor english