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Does the small card have any text on it? such as SD Card, or a branding?
After researching your particular sat nav model, I believe the slot for the card you have received is on the top left as you look at the unit. To insert the card correctly you need to have the screen of your Nuvi facing you, and the brass connectors of the card also facing you, and then slide into the slot until you hear the card click into place. Once the card is inserted you need to power your sat nav up and the maps should be updated.
I have enclosed a photo of the slot that the card should fit into below - hope this helps!
If you need anymore assistance please do not hesitate to respond!
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