I use the Tekans II last year. I had a terrible thing happen with them. I shot a doe at 10 yards with the tekan. It didn't open up!!! I shot her right through the hart and she ran 40 yardsand fell,in the snow with absolutely NO BLOOD TRAIL!!!! When I got to her It looked like I shot her with a 22. Just a little hole and when I gutted her (I wish I took a picture) there was a perfect little hole with no blade slashes right through the middle of her hart. I threw them away and am now using stingers, never using machanicles again. Ive just had to many things happen with machanicles that scare the shi% out of me.