That is for 37mm foam that splits on the ground to spread at the crowd, they are primarily using 40mm foam rounds with a metal core, if you bounce it off the ground it can rotate and impact with the hard plastic backing, which is likely how the UK journalist who required calf surgery was injured. It’s specifically recommended not to bounce them but to aim near the naval, arms or legs.
That is for 37mm foam that splits on the ground to spread at the crowd, they are primarily using 40mm foam rounds with a metal core, if you bounce it off the ground it can rotate and impact with the hard plastic backing, which is likely how the UK journalist who required calf surgery was injured. It’s specifically recommended not to bounce them but to aim near the naval, arms or legs.