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
Faucet Adapter Kits
Impact Double Flat-Edge Spigot Adapter CA-119 B&H Photo Video
GRS Spigot & Spigot Adapter
Linkstar 562604 Spigot Adapter BH-4M8F
Spigot adapter TVMP - bale block
MANFROTTO 013 SPIGOT ADAPTER 16mm spigot, 1/4-inch and 3/8-inch thread
Female Studio Lighting Spigot Adapter 1/4" & 3/8" Thread
Manfrotto 'Universal Stud' Adapter Spigot (013) – AJ's Studio & Camera Supplies
Type 3 Adapter - Metal Press to Copper Spigot Adapter - Multipipe