A question regarding the Stoneskin Geomancer ability. It states that:

"For every 10 hit points the Geomancer possesses (rounded down), she gains an additional permanent 1 ARM or 1 M.ARM, chosen upon taking this ability."

Does that mean that he gains a bonus to ARM/M.ARM based on his max HP when taking the ability, or does the bonus grow as the character's max HP grows?