BlackStar H50B21 - 50 Pitch B-Hub Sprocket - 21 Tooth Pitch-78 The 11/C180 is used for

The 11/C180 is used for high-shock and high-vibration drives

"name":"Gates 14MX-63S-20 Poly Chain GT Sprockets 77192063"

1863-3M-09 has a 3 mm tooth pitch

"mpn":"12/B144-D&D"

BlackStar H50B21 - 50 Pitch B-Hub Sprocket - 21 Tooth Pitch-78 The 11/C180 is used forThe BlackStar H50B21 is a 50 pitch B Hub roller chain sprocket with 21 teeth, precision manufactured from SAE 1045 steel with induction hardened teeth for extended wear life and features machine cut tooth profiles for smooth, reliable chain engagement. Specifications Part Number H50B21 Chain Pitch 50 Number of Teeth 21 Minimum Bore 3 4" Maximum Bore 2" Bore Type Plain Bore Hub Style B Hub Strand Count Single Material Steel Hardened Teeth Yes Outside