I would not buy these: SOG Knives: SOG Fusion Fulcrum I Throwing Knife, 3 Pack, SG-FL11
I have played with similar knives and I see no value to any moving parts on a throwing knife. In fact, it seems to me that you can throw just about any thing that has a point on it. Once you get the distance right and you can throw it repeatably the weight is superfluous. If you get good with it and the weight moves you have to start all over. Secondarily, this knife has a "lanyard hole". Who would put a lanyard on a throwing knife? I guess if you have thirty feet of cord on your knife you never have to worry about losing it. Sort of like a leash or a kite string.