This is the barn door attachment from the Godox AK-R1 accessory kit for Godox’s round head flashes.
However the kit works with any speedlight if you get the $10 round head adapter. This photo was taken
using the grid attachment from the kit. The system is magnetic, so all the attachments just snap on.
The attachments are very useful for close-up photography, and the diffuser dome attachment is
perfect for when you put a speedlight in an umbrella or small softbox. In the past I’ve bought
some questionable accessories for my speedlights, but this kit is a winner.

Best viewed at original size.