I purchased a used Undercover hard tonneau cover off of craigslist, it is the basic for a 5.5ft bed for my 06 f150.

a few months after I got it, one of the struts lost pressure and I was hard pressed to find reasonably priced replacements at the local auto parts store (they were quoting up to 30+ a piece with a week or so wait for shipment)

I went on Ebay and found some for sale from user/store strut-your-stuff-here (http://stores.ebay.com/strutyourstuffhere/) and ended up ordering them.

They snapped right on and off and were a perfect fit for my cover. They were also very responsive to questions I had and obviously shipped right to my home very quickly.

If you need replacements for yours I would recommend them to anyone, I ended up paying 36 (for 2) with 14.90 shipping so came down to 25.45 a piece (well below the quoted price and more timely)

If you find them cheaper local, obviously you may want to go with that but for this ebay purchase, I was very satisfied!

 

also, I should say I am also very satisfied with the cover itself. Really easy to install/remove with 4 brackets and clamps/bolts and rings for hinges in the back. the only mod I needed to do was cut slits in my factory bed linder so that the brackets could sit right (they wouldnt sit outside the bed liner)

I can show pics of this modification and cover on request.

This cover has kept my bed dry from rain, snow and the occasional car wash

 

I have one on my 99. It was literally the first purchase I made for my truck 3 years ago. I keep everything back there. I've just got a regular cab so I have no room up front. I love it. Only time that I don't like it is when I have to haul something of any size.

 

yeah anything tall poses a threat but the darn thing is so easy to take off its not that bad. its pretty light all things considered.

 

I have an UnderCover on my 13' SuperCrew just like the one I had on my 02' Supercrew 12 years ago. Best thing I ever bought for my trucks.

Gained 1 mpg. Easy to take off. Keeps all rain out. Lockable storage. Several people can stand on it at once, makes it easy to clean and wax your cab roof. Cargo light incorporated inside. And fits like a glove.