1 ft (city ruler) = 33.33 cm. The distance of four feet is 133.33 cm. Because the distance of one foot is 0.33 meters, the distance of four feet is equivalent to 133.33 centimeters.
Soft pen calligraphy generally refers to calligraphy works created with soft pen, which should theoretically include brush and soft pen. But at present, there is no such thing as soft pen calligraphy, and there has always been only hard pen calligraphy and brush calligraphy. If you know, you don't have to dig deeper.
Pen calligraphers first put forward the concepts of "hard pen" and "soft pen", and then made the pen a member of the hard pen family and classified the brush into the category of soft pen, so there is a reason why pen calligraphy is better than brush calligraphy.