M8 mandrel already on the tool that is why plastic box is empty -Shorter handle with double compound hinges that maximize leverage -Includes Hand Nut/Thread Setting Riveter -12 interchangeable mandrelsepiece sets included size in Metric M3 M4 M5 M6 M8 M10 M12and in SAE 10-24, 1/4-20, 5/16-18, 3/8-16 1/2-13 Versatile and powerful hand nut/thread setting riveter, takes the hard work out of setting rivet nuts -Ergonomic grip for easy operation, Ideal for working in hard-to-reach area Hand Riveter Kit