Had to look that up and discovered that a “Kicking Strap” is another word for a Vang, said Ronald 🤔
When under sail, one of the most important important control mechanisms we have to help trim the mainsail is the vang or kicking strap (kicker).
We tend to call a line/pulley based mechanism a kicker or kicking strap and a rod or hydraulic system a vang, but the names tend to be fairly interchangeable in the sailing world, even amongst crew on the same boat!
https://www.jollyparrot.co.uk/blog/how-to-use-the-kicking-strap-or-vang
Yes, very poor instructions for a first time builder!
https://footy.rcsailing.net/bobabout/materials-list.html