https://erwtubeline.en.made-in-china.com/product-group/FqdTfpZUCgYI/HG50-Tube-O-D-16-50-8mm-catalog-1.html
HG50 (Tube O.D. 16-50.8mm) - Hebei Tengtian Welded Pipe Equipment Manufacturing Co., Ltd. - page 1.
China HG50 (Tube O.D. 16-50.8mm) catalog of High-Performance ERW Welding Equipment for Stainless Steel Tubing, Advanced Hg50 Fully Automatic ERW Hf Welding...
https://www.rei.com/product/801282/shimano-sora-cs-hg50-9-speed-cassette
Shimano Sora CS-HG50 9-Speed Cassette | REI Co-op
The Shimano Sora CS-HG50 9-speed cassette with a 12-25 teeth gear range provides fast and responsive indexed shifting.
shimano soracsspeedcassetterei