An incredibly attractive piece.
A BO series banknote, where the letter "O" is a font of identical typeface to the numeral "0".
With the 7-digit number 2222220 we get visually a kind of "over-radar" by interpreting the letter as digits we have visually an 8-digit radar 02222220 B-series.
Of course, formally it is an over-radar, but visually the effect is super-attractive.
Excellent item.