Last weekend I installed an invisibleSHIELD screen protector on my Garmin GPSMap 60CSx. I became interested in this product after reading rave reviews on Groundspeak, the geocaching message board. My tendency to crash my mountain bike and scratch my GPS didn't hurt either.
The Invisible Shield installation was very easy. I did end up with some micro-bubbles which the instructions said would work their way out over the next 2-3 days. The bubbles did get smaller, but they were still there. So I took a pushpin and popped them, then used the supplied squeegee to remove the rest of the air from underneath them. Screen visibility is impacted in only the most minor manner, and the benefits of protecting the screen far outweigh any downsides. I just wish I would have had this when I purchased the unit.
My only question now is whether or not I should use this on my nuvi 660, since the mount occasionally pops off the windshield!
And before I forget, the invisibleSHIELD isn't limited to GPS receivers. You can get it for your iPod, cell phone, PDA, and more.
You can also buy the InvisibleSHIELD from Amazon.
The video below is a little annoying at times, but it is still a good overview of the installation process, and it offers other insights into the product.