This string pack was manufactured and sold by the "National Yo-Yo and Bo-Lo Co. Ltd., Toronto - Montreal". An all English pack. Bi-lingual packaging was not yet law in Canada at that time. This same string pack is what I remembered buying as a child.
"Mr. Yo-Yo says: 'These are the strings used by Uncle Al Gallo The World's Yo-Yo Champion'."
Identical to the "3 strings for 10 cents" pack and the "2 strings" pack both made by the same company but released at different times.