I can see how extra momentume/kinetic energy could help people wanting to use mechanicals and are at the bottom needs to use them i.e. everyone says that magic number of 60lbs KE for most mechanicals. Now what I want to know (and it may be hard to calculate) is...how much this might add to momentum or Kintetic Energy...I think MOMENTUM is key. Kinetic energy really isnt the best way to determine effectiveness for penetration. If this product increased momentum by 10% or even better 25% and greater I think it would be a great product. Some people may only get 90% penetration on say a quartering away shot at 30-40 yards, but with 10-25% more momentum they might get complete passthroughs. I would be worried though that this product will throw off the FOC since it is at the back of the arrow. An arrow company would be WISE to develope a mechanism like this, but inside their arrows towards the front. If you take a weight...say 30-50 grains and allow it 2-3 inches of travel inside the front portion of the arrow...now that would create some awesome extra punch!