The 50mm x 1830mm (2" x 72") size is a common size for Knife Grinding machines.
Abrasive belt kits to enable the production of a quality finished knife, these can also be used for Woodworking tools.
These 50mm x 1830mm abrasive belt kits come in three sizes; Basic, Small and Medium, see below for details on the Small Pack.
 
The Small Pack 
A reasonable number of belts to enable the production of a quality finished knife, contains the following belts;
  Grinding primary bevels prior to heat treatment:
    - 4 x P36 grit Ceramic belts 
    - 2 x P120 grit Ceramic belts
 To satin finish:
    - 1 x Fine Surface Conditioning belt
  Polishing:
    - 1 x Cleaning and polishing Belt
  Finish primary bevels: 
    - 1 x P200 grit 3M Trizact A100 Gator Belt 
  Refine cutting edge:
    - 1 x P400 grit 3M Trizact A45 Belt