My son blew up about six balloons and I gave him about four differant knives including a really dull kitchen knife. He was able to bounce the balloon off of this knife. I have a couple customs and these made popping balloons fun. You notice that the sharper the point, the louder and quicker the pop. My 3 1/2 year old comes and is sitting on my lap and my son has a mini audience. The sharpest knives brought the best pops and for some reason we all were laughing and cracking up.I dont know why it hit us as being so funny. I think because a sharp knife pops a balloon REAL fast. It really made knife testing a lot of fun for myself and the kids.