Description: Durable and practical. Special angled slots increase rigidity. Protects tool holder from contaminants. Better overall balance of tool holder assembly. With high precision and strong holding force. Suitable For: Boring, milling, drilling, tapping, engraving, CNC, spindle machines, and other processing. Specification: Model: ER11 Material: 65 manganese Height: 1.8cm Bottom Diameter: 0.8cm Center Hole diameter: 3.5 mm Package Includes: 1 Piece ER11 Collets Note: Due to the quality differentiation of monitors and lighting effect, the picture may not reflect 100% the actual color of the item Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid