U.S. #BK226A $6.40 (Blue) Flag Over Porch, #2920f
#2920f is a pane of 15 plus label. The label is located in the sixth or seventh row of the pane and is die cut. If the label is removed, an impression of the die cutting appears on the backing paper. Postal Item No. 3633X for booklets with the label in 6th row of the pane, and Postal Item No. 3633 for booklets with the labels in the 7th row of the pane
BK226A-B and BK227 are called makeshift vending machine booklets. These booklets, plus BK273-BK258, are known as 'The Blues' for the blue cover jacket they share in common. The text on the front and back changs to describe the contents of the booklet.