These four blue-aqua block LRIs are from the same mold, they just have a longer saddle leg. The mold was filled more on the taller ones, and less full on the shorter ones. This is the most common style of Block LRI, I believe. Called by some the "D" opening block. The one end of the opening is round, like others, but then the other end has a unique D shape to it. Most common in blue-aqua and light aqua. Also found in cornflower blue.