Lowrance GlobalMap 4000M Operation Instructions Manual page 26

WARNING:
When the unit is mounted in an unprotected area, such
as an open boat cockpit, the protective face cover must
be removed when the vehicle is moving at high speed.
This includes towing a boat on a trailer at highway
speeds. Otherwise, wind blast can pop off the cover.
Now that you have your unit installed, move on to Sec. 3, Basic GPS
Operations. There, we'll present a series of step-by-step tutorials to
teach you the basics of your sonar operation.
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