guitar scale
C Phrygian
C1D♭♭2E♭♭3F4G5A♭♭6B♭♭7
Minor with a flattened second — the half step right above the tonic is the whole character.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
CHD♭WE♭WFWGHA♭WB♭WC
What is true of it
C Phrygian is C, D♭, E♭, F, G, A♭ and B♭, and back to C.
Its steps are H – W – W – W – H – W – W, where W is a whole step and H a half.
On the same tonic, C natural minor differs from it by exactly one note.
Across the first twelve frets of the guitar its notes fall in 43 places, which is what makes a scale a shape rather than a list.
Chords made only of these notes
Found by testing every chord in the catalogue against these 7 sounds, not chosen.