Product review (4 stars): The Kit fits 2007 Whirlpool Duet...
My 2007 Whirlpool duet dryer had that loud screeching sound that so many others have experienced.  I figured that I might as well replace all these parts since I would have the whole machine apart anyway so, I ordered this kit on Monday, using the free economy shipping option.  Wasn't expecting to receive it so fast but it arrived 2 days later, on Wednesday evening.  I had the dryer back up and running within a couple of hours that night.  Everything was shipped in a single plastic bag, packed in a padded envelope.  I used every piece that was provided - four drum wheels, tensioner pulley, drum belt, 9 Tri rings and a bushing.  I don't know if these were actual Whirlpool parts, the packaging was vague.  But, the quality was as good or better than the parts I removed.  I replaced the four drum wheels, but the old ones seemed to be fine.  The culprit was the tensioner pulley, which had some black plastic residue melted to its bearing surface causing the pulley to seize. It was probably the remains of the original Tri ring, which was missing.  I'm thinking it must have melted, burned up and shredded since the black residue was also spread around the area.  Shop vac took care of the residue and I used a fine abrasive pad to clean the fused plastic off of the bearing shaft.  Im not sur wife it was necessary but, I put a drop of Teflon lube on each bearing surface during assembly.

Taking the front of the dryer off and getting it back together was the most challenging part of the job.  Lots of screws, which for the most part, are pretty easy to locate.  The tricky part was getting the top control panel off.  It is permanently attached to the trim ring which goes around the door opening and the whole assembly is fastened to the cabinet with a bunch of hidden spring clips.  Be careful releasing the metal spring clips, they are fused to the trim ring and will break off pretty easily.

The whole job took under 2 hours to complete.  It would have been nice to have some instructions included but, there is plenty of how-to help online which is easily found.  Good luck!