I have the BakFlip folding cover and like it a lot. Yes, it does take away space when all the way up against the back window, mine is about 10" when folded up. They make a roll up cover too, but it uses space when rolled up. You may have luck visiting the web sites of the various manufacturers and get the specs you want from them. Mine is www.bakflip.com
2012 3055RL Big Horn - Dexter upgraded axles - G rated LT Tires
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2013 F350 DRW 4x4 Crew King Ranch