U-2 and SR-71 Blackbird, the diving suit, rebreather, scuba diving gear, and many others. Many space suit designs are taken from the U.S. Air Force suits, which are designed to work in "high-altitude aircraft pressure[s]", such as the Mercury IVA suit or the Gemini G4C, or the Advanced Crew Escape Suits. Glove technology The Mercury IVA, the first U.S. space suit design, included lights at the tips of the gloves in order to provide visual aid. As the need for extravehicular activity grew, suits such as the Apollo A7L included gloves made of a metal fabric called Chromel-r in order to prevent punctures. In order to retain a better sense of touch for the astronauts, the fingertips of the gloves were made of silicone. With the shuttle program, it became necessary to be able to operate spacecraft modules, so the ACES suits featured gripping on the gloves. EMU gloves, which are used for spacewalks, are heated to keep the astronaut's hands warm. The Phase VI gloves, meant for use with the Mark III suit, are the first gloves to be designed with "laser scanning technology, 3D computer modeling, stereo lithography, laser cutting technology and CNC machining". This allows for cheaper, more accurate production, as well as increased detail in joint mobility and flexibility. Life support technology Prior to the Apollo missions, life support in space suits was connected to the space capsule via an umbilical cord-like device. However, with the Apollo missions, life support was configured into a removable capsule called the Portable Life Support System that allowed the astronaut to explore the Moon without having to be attached to the space craft. The EMU space suit, used for spacewalks, allows the astronaut to manually control the internal environment of the suit. The Mark III suit has a backpack filled with about 12 pounds of liquid air, as well as pressurization and heat exchange. Helmet technology The development of the spheroidal dome helmet was key in balancing the need for field of view, pressure compensation, and low weight. One inconvenience with some space suits is the head being fixed facing forwards and being unable to turn to look sideways. Astronauts call this effect "alligator head". High-altitude suits Evgeniy Chertovsky created his full-pressure suit or high-altitude "skafandr" (скафандр) in 1931. (скафандр also means "diving apparatus"). Emilio Herrera designed and built a full-pressure "stratonautical space suit" in 1935, which was to have