Description

This is a 13mm diameter ball bearing and a 4mm thickness. 
The inner diameter of the bearing is 4 mm and is well suited for screw with M4 screw, the sides of the bearing are closed to prevent dust from entering, and the outer wall of the bearing has a groove about 1 mm deep. 
These bearings are used in some 3D printer heads used to create pressure on plastic to push it into the printhead with a small gear. 
A 1 mm slot is suitable for 1.75 mm diameter plastic. 

Properties:

• External diameter: 13 mm
• Inner diameter:  4mm
• Thickness:    4mm