These are often refered to as "dry cut saws." I have had one for about 10 years. I dislike abrasive cut off 'saws' because they make sparks (fire hazard), burs, stink, produce airborn ditritus, and leave the cut off ends G_d-awful hot. A dry cut saw cuts clean of burrs. It produces metal chips, not a mixture of airborn fine metal and abrasive dust. It does produce a little heat but I can handle the cut off end and fit it immediatly in place.
Blades are pricy but I make thousands of cuts with one blade. Yep, you cannot cut hardened materials--best only for mild steel.
Ciao,
David