M8 mandrel already on the tool that is why plastic box is empty . RZX is professional of rivet nut tool filed.We have more than 10 years experiences in rivet Nut tool.We are the the first company sell on Amazon since2014. We more know Rivet nut tool. We only supply”simple,classic,save effort,sturdy,” tool,also our price is competitve.No doubt,we are you best choice. 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