Recently I swapped out the HF DC impeller, for the larger Rikon impeller.  I did this to try and delay, for a little while, replacing the HF with a real DC.  I ordered the RIkon impeller and with shipping it was $119.00.  The swap was easy, remove 12 screws for the impeller cover, remove a reverse threaded hex bolt and washer.  I used a small puller to start removing the old impeller and then pulled it off by hand.  Put the new impeller on and screw everything back together.  The HF impeller is