The Fein tool is one of the best investments I've ever made in tools;  it has accomplished things that no other tool would, e.g. cutting through 2" thick 100+ year old heart pine (it pings when hit with a hammer, it's so hard).  Not with these blades, though!  These began to break teeth off within minutes of use on SOFT new pine.  I've had the tool for several years now and used it for countless tasks but, even having so much experience with it, I thought I might be twisting or pressing on this blade somehow.  It didn't matter how careful I was, though, teeth continued to break off until only about a third were left.