Valentine I have to agree with Bigbuck 17 on the fact that there are the lovers and the haters.
I will fall in the category of they have not let me down yet.
I have had one open when I was practicing and that was not pretty but I got good penetration into my tool box. I needed new O rings and thought I would try some from my shop and I have to say not a single head has open and I have try to hit them against stuff to get them open and they dint until the head enter something. So I will still be using them this year. Has for flight I get a 1 to 1.5 inch highest derffernce with a feild tip at 30 yards at 25 they are dead on.