Which file should I choose?
Use 1SCC318133F0001.dxf (revision B) to insert the supplied editable drawing into your layout. The ZIP contains the unmodified 1SCC318133F0001.dxf.
Use OS1250_D_B_22.IGS.igs (revision A) to place the original solid geometry in your 3D assembly. The ZIP contains the unmodified OS1250_D_B_22.IGS.igs.
