So, if you're looking at HxD, one line represents 16 bytes. 1 Hexadecimal letter, like let's say B, is a half of a byte. So you'll have 16 sets of two Hexadecimal characters like this, for example:
A1 56 31 4D 8A 09 7A 3C 01 90 AC B1 51 0A 1B 11
This is what your SD Key MIGHT look like...