1/4" and 3/8" Male Threaded screw Adapter Spigot stud 713095343852 | eBay
Amazon.com : 2 Pieces Standard 1/4 to 3/8 inch Metal Male Convertor Threaded Screw Adapter Spigot Stud for Studio Light Stand, Hotshoe/Coldshoe Adapter, Ball Head, Wireless Flash Receiver, Trigger : Electronics
Amazon.com : (2 Packs) 32mm 1/4" to 3/8" inch Female to Female Convertor Threaded Screw Adapter Spigot for Studio Light Stand, Hotshoe/Coldshoe Adapter Ball Head Flash Trigger Receiver : Electronics
Kupo KS-128 3/8”M-3/8”M ADAPTER SPIGOT
Double End Stud 1/4-inch And 3/8-inch Adapter Spigot Threaded Screw Connector For Flash Light Stand - Screws - AliExpress