The gyros, accelerometers and pendulums contain almost frictionless nitrogen gas bearings. These required very precise machining and very small gaps between the bearing surfaces. Dimensions were held to tolerances of , and the gap filled by the nitrogen is about . Nitrogen entered the gyros at about 15 psi and was vented to space via a pressure regulator in the bottom of the ST-124 that opened at 13 psi. The large silver sphere to the left of the ST-124 held the supply of nitrogen for the bearings.