I don't know why people can't understand. There are no instructions, of course, but it's not rocket science. Use a screwdriver to loosen the screws, use a pick like thing to pry the brain out of your old strap, insert it into the new strap and tighten the screws. Fitbit Charge is perfect. The only issue I have and why it doesn't get five stars is that it opens/removes from my wrist more easily than the original strap.
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