I get this on Ebay recently!
21-Feature --A Lion Match Co. trademark for a match book containing wide match sticks that were printed with lettering, designs or a combination of both (not to be confused with printed sticks). The standard 30-stick size match book held 21 wide stick feature match sticks in three rows of seven. The 20-stick size match book held 15 wide match sticks and was known as the Feature. Introduced September 1930. They are no longer made.