German Ruled Exercise books

Books are ruled with 4 lines for writing - two blue centre lines and two pink outer lines.  These lines allow correct positioning of 'tails' above and below the bodies of the letters.  There are three different sizes - year 1 is 7mm apart and includes an extra dotted blue line in the centre for correct positioning of parts of letters such as the crossbar of the 'e'.  Year 2 is 6mm apart and year 3/4 is 4mm apart.