There is no text display on a 1640 also this model doesn't have voice capability. Now, in order for the compass to properly function the unit does need to be calibrated. There is a sticker on the bottom of the unit that gives step by step instructions.
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There is no text display on a 1640 also this model doesn't have voice capability. Now, in order for the compass to properly function the unit does need to be calibrated. There is a sticker on the bottom of the unit that gives step by step instructions.