If you are the Person/Person's throwing the rocks what does this prove? How high in the air do you have to throw this 2lbs rock to prove that the ice will hold a 200lbs person? If the first rock does not go through the ice then what will the second rock that you toss tell you? Is there a noise or a voice that you are listening for that tells you your good to go ahead and walk out . These so called ice testers that you are chucking are along the shore for a reason they were put there to stop the shore from eroding. When it snow's and yes it will snow these so called ice testers are now trip hazards, They damage Snowmobile, ATV, Sleds,