55 mm x 120 mm x 29 mm NKE 6311-2Z deep groove ball bearings

Deep Groove Ball Bearings offers a 55 mm x 120 mm x 29 mm NKE 6311-2Z deep groove ball bearings selection of Genuine Deep Groove Ball Bearings at Wholesale Prices. 5.9400 in slot spacing: We Dacheng mechanical equipment manufacturing Co., Ltd are a 55 mm x 120 mm x 29 mm 55 mm x 120 mm x 29 mm NKE 6311-2Z deep groove ball bearings Certified Parts Retailer

What is 6311-2Z bearing interchange？