Polaris
Polaris is a tritave-repeating rank-2 temperament that tempers out the comma 177147/171875 in the 3.5.11 subgroup, the amount by which 7 11/5's fall short of 15/11. It enables 9:11:15 no-twos chords. Polaris temperament is to Arcturus as meantone temperament is to Pythagorean tuning.