Which of these protects a horse's lower leg from an injury that may occur during exercise?

So envious of the easier and modern products now. Must be so good to just slap that wonderful stuff known as Velcro together and voila - you're fastened up. In my day we had to do up at least half a dozen buckles on each boot - and it wasn't much fun in the middle of winter with wet boots frozen fingers😂

when I go horseback riding I put splint boots