Thorlabs - AS25E6M Adapter with Internal 1/4"-20 Threads and External M6 x 1.0 Threaded Stud
M20 to 1/2" Inch NPT thread adapters. ( $8.44 Each - Sold in 10 Packs ) M20X1.5 threads external side. 1/2" Inch NPT threads internal side. plated brass adapter with o-ring gasket. - Walmart.com
Otc Threaded Adapters, Spread 3/8-16 (Ex.) In 8005 | Zoro
threaded adapter
Amazon.com: OTC (8007) Standard External/Internal Threaded Adapter : Automotive
Amazon.com: Hotop 2 Sets NPT 3/8 Inch Stainless Steel Male and Female Quick Connector Kit Pressure Washer Adapters(Internal Thread, External Thread) : Patio, Lawn & Garden
Amazon.com: OTC (8007) Standard External/Internal Threaded Adapter : Automotive