This is a Beckman JS-4,2 4200 RPM Series 6 Bucket Rotor which includes the Blue lid, the 6 Blue (3) 1061G (3) 1062G JS-3.0/JS-4.2/JS-4.2A swinging buckets with orange inserts. It also comes with the center mounting bolt. Everything you see in the photos.
This actually reads. TY.JS.4.2 on the black rotor.
This came off a J6-Mi Refrigerated Centrifuge. Feel free to ask questions. Look for more parts coming for this centrifuge