Squareness ratio is mediocre, around 0.75, resulting in early but smooth onset of distortion. However, raking the blade compromises the squareness of the edge. The four disk method is one way to verify overall squareness. The name "squareness gun" was coined by Rose Tyler in the earlier episode. The name "squareness gun" was coined by Rose Tyler (Billie Piper) in the former episode.