Some areas of the country do throw the weight in youth competitions. If you or one of your athletes is scheduled to throw in a youth meet, you will need to contact the meet director and check what size weight they will be using for the age group.
In the sense of performing as designed, most radar detectors do detect the presence of police radar in the immediate vicinity of a speeding vehicle. Whether or not that information will actually prevent a driver from receiving a speeding ticket remains to be seen, however.
Doppler/microwave sensor can detect motion through most non-metallic blocking obstacles (walls, curtains, glass/windows), and when movement is detected the light comes on without any delay even before entering into the space that is being illuminated