I've been reading all the Spine Whack test threads. I have never bothered to test my folders, but last night I had the idea to test one of my knives, A Buck 889. I barely tapped (noticed it didn't say whacked) the blade and it closed right up on the third tap. I tried it a few more times and it was always on the third tap. I guess that knife won't be out of the storage bag much from now on.