First of all not I am a NOVICE. I own a graphics shop in my retirement. 45 Yrs as a Master Machinist. so I take math serious. 1) Blades are sharp, test cut on a US Cutter MH721. 2) Holder I received may have slipped through quality assurance. The barrel as you can see in the measurement photo of oem blade holder and the amazon bought is not close, it will fit in the machine. But only if you back the holder knurled locking nut all the way out. The overall height with a 60 degree blade is way off also. If you use the flange to set your height consistently with an oem holder, I found the blade even retracted to half the thickness of a credit card did not give consistent cuts. I Use Oracal 651 so it's not the vinyl. Several times the blade would barely score, and on same piece would cut through backing paper. and a few times literally dragged the vinyl from under the pinch rollers. Biggest complaint is, if you manually plunge blade up and down, the blade drags during extension and retraction, and there is metal to metal grinding coming from the holder. I sprayed wd40 into blade hole and worked it 20 times, the wd40 comes out gray. Metal shaving. Not returning it, because blades will do what I need. This review is based on my MH cutters. you may have better luck.