Counter Strike Source

[Wha?]

Newer flashbangs may have the rubber balls in them, but it's the bang that stuns, and why they aren't used around children. A child's inner ear gets irreparably damaged by the bang (which is loud enough to make you lose your sense of balance for up to 5 seconds).

I'd be worried about rubber balls.. they would bounce (since they would be elastic, or they'd kill everybody ala claymore mine) and that delays entry.