connected at the wearer's waist, circulated through the suit to provide cooling, and exited through a hose on the right side of the helmet, or through the face opening depending on whether the faceplate was closed or open. A small pressure bottle connected by a small hose to a connector next to the astronaut's left jaw was used to pressurize a pneumatic seal when the faceplate was closed. Replacement of the dark gray nylon outer shell with one made of aluminum-coated nylon, for thermal control purposes Replacement of the black leather safety boots with ones made first from white coated leather, later aluminumized nylon-coated leather, again for thermal control. Introduction of straps and zippers to provide a snug fit, along with refinements in the shoulder, elbow, and knee retaining cords Special gloves with four curved fingers for grasping the controls, with the middle finger made straight for pushing buttons and flipping toggle switches. (In the book We Seven, the astronauts pointed out that the special design of the gloves allowed them to avoid the use of a "swizzle stick" for the buttons and switches.) A "biomed" flap on the right thigh for the connection of biomedical sensors to the spacecraft's telemetry systems. Each astronaut had three pressure suits: one for training, one for flight, and one for a backup. All three suits cost US$20,000 total and unlike the military Mark IV suits, had to be individually tailored to each astronaut. No Mercury pressure suit ever failed during launch. No crewed Mercury capsule ever lost pressure during a mission, so the suits never needed to be inflated after launch. The only suit-related incident was an uncapped ventilation inlet valve which almost led to the drowning of astronaut Gus Grissom: at the end of the MR-4 mission the hatch cover blew off while in the Atlantic Ocean and the capsule began to fill with water, forcing Grissom to make an emergency exit without securing his suit for the recovery operations. The most frequent suit complaints of the astronauts were discomfort due to poor temperature control, and inability to turn the head within the pressurized suit. Specifications Name:: Mercury Spacesuit Derived from: Navy Mark IV Manufacturer: B.F. Goodrich Company Missions: MR-3 to MA-9 Function: Intra-vehicular activity (IVA) Pressure type: Full Operating pressure: Suit Weight: 22 lb (10 kg) Primary life support: Vehicle provided Backup life support: Vehicle provided Later modifications After the MR-3