Parts for ball bearing 6004 (internal diameter Ø20 and external diameter Ø42): Compression rings for ball bearings for Ø42 Stainless steel Quantity: 15 pcs. Supporting rings for Ø42 Stainless Steel Quantity: 30 pcs. Supporting rings for Ø20 Stainless steel Quantity: 30 pcs. Shim rings t=0,5 for Ø42 Stainless steel Quantity: 30 pcs.