NASA's National Aeronautics and Space Administration (NASA) is seeking to procure replacement optical viewports for the Hypersonic Materials Environmental Test System (HYMETS) at the Langley Research Center. The procurement involves acquiring new fused silica optical viewports to replace aging units that are critical for optical diagnostics, with specific requirements for quantities, configurations, and coatings, as well as the welding of threaded adapters. The urgency of this procurement is highlighted by the degradation of existing viewports and the need to meet operational requirements before funding expires on March 28, 2025. Interested vendors must submit their capabilities and qualifications in writing to Kimberlynn Lancaster at Kimberlynn.m.lancaster@nasa.gov by 4:00 p.m. Central Standard Time on April 8, 2025, to be considered for this sole source contract with MDC Precision LLC.