Graco 6110 Owner's Manual page 52

6. Push the infant restraint down into the base
and make sure that you hear a "click" .
Pull up on the infant restraint to be sure
it is latched securely into the base.
If the infant restraint does not securely
latch into the base, the infant restraint
provides NO protection for your child.
DO NOT use the infant restraint/base
if the infant restraint does not securely
latch into the base.
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