Product review (5 stars): Good product
This product is a must if you need to get your dryer closer to the wall.  We found a version of this product at one of the "big box" stores for a few dollars cheaper, but the quality was visibly poorer - the "big box" version was flimsier and only electrically spot welded, as opposed to the Whirlpool, which has properly finished and folded-in seams.

Installation was fairly easy and the product comes with instructions, but you'll likely need a pair of tin snips to cut the excess material away once you've determined the proper size.

You will want to buy some foil tape (check the "Frequently purchased together" section), to tape the seams off after you've got the periscope to the proper size.  It's important as this will prevent the vented exhaust from leaking into your laundry area.

Overall, a great product!