Downspout Extension Flip-Up Hinge for 3x4 Downspout (3X4 A, Clay-Latch) - Amazon.com
3x4 Style A Downspout Flip Up Hinge | Made in The U.S.A. | Also Includes Screws, Aluminum Latch & Instructions | Easy DIY on 3x4 Downspouts (Black) - Amazon.com
Patented Pro Flip Downspout Extension latch - YouTube