Brass bushing of 8mm de diameter
Brass bushing for 8 mm linear guide with outside diameter 12 mm and length 15 mm.
They are usually used on create sliding charriot on steel axle. The brass slides very well on stell, just add some grease.
You may find such bushing into DIY 3D printer or homemade mechanical moving part... those bushing are really great tool to use with 8mm axis (axis that you may find into standard printer that you can disassemble).