SolidWorks 2014 Tutorial | Smart Mates 

Excellent explanation. Thank you.

Ctrl dragging a part also copies the part you drag out

Can you do the same type of concentric mate with a shape it is not a circle?

so simple thnx

lol it was silent for the first few seconds so I turned up the volume and then "IN THIS LESSON.." but thanks this really helped. However, I just finished an assignment for an assembly without any prior knowledge of using the mating tool and I had to fit shafts that were slightly smaller than the holes (loosest fit in engineering drawing terms), I don't remember how I managed to put it together but how would you mate in that case? i.e. a 0.560 diameter shaft into a .563 diameter hole. Thanks