Like Randy, mine are built into the box blade. I did use it for a couple of jobs in the last week and I am impressed. One job was a crushed rock driveway (mine) which had not been touched up in some time. I dropped the scarifers to the lowest position and tore up the material. That took several runs but the 2520 never missed a beat. I then raised the scarifers and used the box blade to smooth it all out. I"ll say it again ........... smooth.:tongue: