I thought these were a thing of the past until I had to rip out the seams of a very well made pillow. I tried everything I could find to rip the seams and finally gave up and ordered this. When it arrived I went to work and had all of the seams ripped in a coupe of minutes. Never again will I waste my time with other objects. You can't reinvent the wheel and there's no need to as long as these are on the market! Super sharp and comes with a clear cover. This is a must have for anyone who sews or crafts. I keep it handy in my sewing box now so it will be at hand at a moments notice.