I use exactly what your describing.  I bought mine at R&B cycles (Big Dog Dealer) in Nashville. $52 plus tax.  They actually suggested them over the set screw "BDM" covers.  Said guys were loing them.  I have had mine since August and they havnt budged. I had to loosen the ignition the get the two inside ones on, so it is impossible for them to come off anyway.  I think they were S&S brand but cant remember for sure.