Bronze Self Lubricating Bushing.
These bushings are an excellent choice for long life, low wear and maintenance. They also have an advantage over linear bearings in that they not only offer the ability to slide linearly along a shaft but also rotate around it - this is needed in machines such as Ingentis/Ultimaker/Tantillus which use rotating rods.
These have and ID of 8mm to suit 8mm shaft, an external diameter of 12mm and a length of 15mm. Weight is 7g