20 Pack Full Ceramic 684 Si3N4 Miniature Ball Bearings 4x9x4mm With PTFE Cage, High Precision Ceramic Bearings For Low Friction, Durable For Industrial, Robotics, And Hobbyist Projects

20-Pack Full Ceramic 684 Si3N4 Miniature Bearings 4x9x4mm
✔️ Full ceramic bearings, 4x9x4mm, Si3N4 balls, PTFE cage, 20 pcs

These 684 full ceramic miniature bearings use Si3N4 ceramic balls and races, featuring PTFE cages for low friction and long life in clean environments. They’re ideal for precision micro-machines, robotics, CNC guides, and model-building projects.

✅ Inner diameter 4 mm, outer diameter 9 mm, width 4 mm
✅ Material: Si3N4 ceramic balls and races; PTFE cage
✅ Cage: PTFE (Teflon) for smooth, low-friction operation
✅ Pack size: 20 bearings per set

💡 What is a full ceramic miniature bearing used for in precision machinery? These handy bearings are designed for small axes and guides where smooth, reliable motion matters.

- handy for robotics and micro-machines in tight spaces
- ceramic Si3N4 bearings reduce friction and resist corrosion
- PTFE cages enable smooth, dry-lubrication performance