These are awesome, high quality, custom made Brass/Nickel spacers.
They are great at making sturdy standoffs/spacings for your projects.
Outer Diameter is 10mm which makes a very stable platform.
Inner Diameter is M5 to give a thicker wall to keep the m5 screw snug and centered.
These spacers can be used in all sorts of builds, and this particular sized spacer is the same as the one's included in our Wheel Kits.

Spacer length: 15mm