Features: HIGH-STRENGTH MATERIAL - forged by high-strength heat treated alloy steel, and the Mandrel Nose Piece Riveter Tip is strong, durable and anti-rust. MARKED STURDY CASE - comes with a colorful sturdy plastic case for storing and classifying the sizes of different chucks. Variouse OPTIONAL SIZE - metric M3, M4, M5, M6, M8, M10 and M12 all together 7 different sizes for choosing. ECONOMIC - Save money and replace the rivet nut mandrel instead of buying a new riveter! UNIVERSAL FIT - Fits many standard nut riveters. Specification: Size: M3/M4/M5/M6/M8/M10/M12 (optional) Material: alloy steel Quantity: 1 pack Storage: colorful Labeled Plastic case Packing list: 1 * M3 Chuck 1 * Storage Box