Apollo Lunar Module Descent Engine (LMDE) Flow Control Valve Splitter, measuring 7.5" x 7" x 3", marked at the base: "QR401574-1B3, S/N Q291." This subassembly comprised part of the Lunar Module propellant system's Flow Control Valve (FCV). The FCVs were used in conjunction with the LMDE Pintle Injector to vary thrust output of the Lunar Module Descent Engine upon command by the Lunar Module Pilot or onboard computer. Developed by TRW, this was the first implementation of throttleable coaxial injector technology, allowing the LM Pilot to regulate the spacecraft's descent rate down to the moon's surface; the technology was subsequently adopted by Space-X for its Merlin Rocket Engine.