Product review (4 stars): Great wheel and here is a sub for the retainer clip not supplied
This worked perfectly.  The only reason I did not give it a 5 star was that the picture seems to indicate there are 2 of them.  The product description does show only one as quantity. If one of the pictures was at a different angle that would be better matched to what you get.  There is NO clip with this and mine was missing.  Don't worry about it too much.  You can find a sub at your local big box store (lowes/homedepot) in the form of a 1/2" E-Clip  I purchased Hillman Part # 881399 and it worked great.  I actually think these are better than the original cheap plastic clips that came with the machine so I changed them all out to these new retaining clips