This is one of the reasons I dread leaving my PRS-505. I have the lightwedge cover and it is the perfect companion for night reading! I even bought a second one on eBay when they discontinued it in case my first one breaks. My theory is that as long as the screen is 6" I can use a rubber band to attach the thing to my reader somehow. I tried this with my PRS-505 outside of the case and it worked pretty well (I still perfer it in the case). Anyway, this is a huge issue for me since at least half of my reading is done in bed at night with my wife sleeping next to me. My solution prior to the lightwedge was to get one of those camping head lights and point that at the reader. It works well but is not very comfortable and if I rolled the wrong way I scared the@#$@# out of my wife
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I have not read about the light cover they have for the 600 but looking it it I can't believe it would put out enough light.
-Greg