Before I bought a SD Card for my Zumo, I thought I'd ask Garmin what is the largest capacity card the Zumo can handle. The owner's manual does not address this. Excerpt from Garmin tech email reply to me today: "The largest SD card that this unit will hold is a 2 GB card. Currently, the only unit that holds up to a 4 GB card is the Nuvi 660. Should you have further questions please contact Garmin Product Support by replying to this email or contact our Consumer Support Line at 800-800-1020 Monday-Friday 8am-5pm CST. Chris Malcolm Automotive Support Specialist Garmin International 1200 E. 151st Street Olathe, Ks 66062 Phone 800-800-1020 Fax 913-440-5488 www.garmin.com"