I carried my blackjack for years until my agency outlawed them. It now sits in a drawer w/my other LEO stuff. These were very effective tools that filled the gap between talk and shoot. The expandable baton replaced the blackjack/slapjack but are used similarly so I'm not sure what was accomplished. The blackjack fit in a pocket and reduced the gear worn around your waist.

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Old Cop
LEO (Ret.)