John F. Maulbetsch (June 20, 1890 - September 14, 1950) was an All-American football halfback at Adrian College in 1911 and for the University of Michigan Wolverines from 1914 to 1916. He is also a member of the College Football Hall of Fame. After playing with an independent football team in Ann Arbor and at Adrian College, Maulbetsch became one of the most famous American football players in 1914 while playing for the University of Michigan. Maulbetsch became known as the "Human Bullet" because of his unusual low, line-plunging style of play, and was also known as the "Featherweight Fullback" because of his light weight and small size.

Much of the attention on Maulbetsch focused on his diminutive size and unique running style. At 5 ft 7 in (1.70 m), and 155 lb (70 kg), Maulbetsch was a small back, even by the standards of his day. And his running style saw him bend his torso and propel himself like a projectile into the opposing line. Indeed, he won several nicknames based on his size, running style, and fighting spirit, including the "Human Bullet," "Mauly", the "Human Shrapnel", the "Featherweight Fullback", the "Michigan Cannon Ball," and the "German bullet." Comparisons of Maulbetsch to military armaments were common. In addition to the "bullet", "shrapnel", and "cannonball" nicknames, the Syracuse Herald observed: "Standing up in front of a Krupp gun has its dangers, but it is not to be compared with the dangers of standing in front of Maulbetsch when he is going full speed ahead." Maulbetsch's style was described as "line-plunging." A New York newspaper noted: "When the ball is snapped to him he almost doubles himself up, and, with his head aimed at the knees of the opposing line, he dives head first. Those who have seen Maulbetsch in action marvel at the great momentum he can get up in two or three steps." Noted football writer Walter Eckersall said: "Mauly is a little fellow, being built close to the ground. They say that when he plunges at the line his head is almost on a level with his shoe tops - that he hits so low that it's well nigh impossible to stop him." An Iowa newspaper wondered how it was possible "for a man to smash into a line of human bodies with the force that Maulbetsch does and come out of the game without a broken neck." Maulbetsch was said to run "so low that he could dash under an ordinary table without losing his feet." At a coaching conference in the 1920s, a coach doubted the table-ducking story and challenged Maulbetsch. The doubter later recalled: "I began ribbing him about this table-ducking stuff and finally offered to bet him he couldn't do it. Well, we got a table up in a room, Johnny tucked a water pitcher under his arm and backed against the wall. Darned if he didn't do it, the only thing, that water pitcher broke in a million pieces." Asked about the incident, Maulbetsch said it was true, except one part. Maulbetsch insisted there wasn't a nick on the pitcher.

Using a quote from the above article, answer the following question: What features made him the Human bullet?
his diminutive size and unique running style. At 5 ft 7 in (1.70 m), and 155 lb (70 kg