Standard sizes for cans that food is stored in, usually only found in really old recipes:

Can No.   Approx. Weight     Volume
    #1          10-11 oz   1 1/4 cups
  #300             15 oz   1 1/3 cups
  #303        1 lb         2     cups
#1 tall       1 lb         2     cups
    #2        1 lb  3 oz   2 1/2 cups
 #2 1/2       1 lb 13 oz   3 1/2 cups
    #3     1 qt 13 fl oz   3 1/2 cups
    #5        3 lb         5 3/4 cups
   #10        6 lb  8 oz   12-13 cups