Dymo LabelWriter SE300 User Manual page 16

Below is a graphical representation of how this works.
To send a value under 256 to a command that takes the n1 n2
parameters, simply send the first character with a 0 value. For
values greater than 256 but less than 512, the first parameter
should be sent with a value of 1. For values greater than 512 but
less than 768, the first parameter should be set to 2, and so on.
Conversions
Converting from dots to inches using the n1 n2 parameters can
seem a bit challenging at first, but is really no more complex than
multiplication and division. The table below lists some common
values and their relationship.
Inches
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4-12
Dots n1 n2
101 0 101
203 0 203
304 1 48
406 1 150
507 1 251
609 2 97
710 2 198
812 3 44