This "Slewing ring bearing" consists of a combination of stainless steel balls with High grade polymer inner and outer rings that enables dry operation with low co-efficients of friction.
The Xiros® swivel ring bearing can be used at temperatures up to 80 °C.
Lubricant- and maintenance-free
Smooth and Light
Explanation and technical information here:
a) with 3D printed plates:
b) with aluminium plates: