A.C. Lighting Inc. - Entertainment Lighting Technologies | Double End Stud (1/4''-20 & 3/8'') Adapter Spigot
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