Amazon.com : Manfrotto 016 Adapter Converts Standard 5/8" (16mm) Female Light Stand Tip to 1/4" x 20 Thread on a 12mm Shaft,Silver,3 x 3 x 3 inches : Photographic Light Mounting Hardware : Electronics
Manfrotto 195 5/8" Male to 1/4"-20 Screw Adapter 195 B&H Photo