Overview Product Description Vacuum Tube Plate/Anode Cap. 9/16" (.5625) steatite fits tubes such as 3B28, 572B, 811A, 813, 866A, 872A, etc. Product Videos Custom Field Product Reviews Write a Review Write a Review × Tube Cap-9/16"-steatite-811,572B,etc (Item: CAP-.5625-C1) Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Review Subject * Comments *