Vaja Cases has released a great leather case for the Garmin iQue 3600. Here is some info and a photo of the case.

Features:
Snap Closure
Easy access to scroll dial & function buttons
Mic & speaker stainless steel mesh
Adapter/Headphone jack access
Optional Ultra Clip
Custom Built Option Available
1 1/8" x 2 6/8" x 5 3/8" inch.

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