The question "Which metal detector 2?" is not clear. It seems to be incomplete or missing some context. If you could provide more information or clarify the question, I would be happy to help you find the right metal detector for your needs. **

A metal detector itself is not dangerous, as it is simply a device used to detect the presence of metal. However, the way in which it is used can potentially be dangerous. For example, if someone is using a metal detector near electrical wires or other potentially hazardous areas, there is a risk of injury. Additionally, some metal detectors may emit low levels of radiation, so it is important to follow safety guidelines and use the device responsibly. **

A metal detector detects bones as metal because bones contain minerals such as calcium and phosphorus, which have conductive properties similar to metals. These minerals can create a signal that is picked up by the metal detector, leading it to identify the bones as metal. Additionally, bones are dense and solid, which can also contribute to them being detected as metal by the device. **

A metal detector recognizes bones as metal because bones contain minerals such as calcium and phosphorus, which are conductive and can create a signal similar to that of metal when exposed to the electromagnetic field generated by the metal detector. This conductivity allows the metal detector to detect bones as if they were metal objects. Additionally, bones are dense and solid structures, which further contribute to their ability to be detected by a metal detector. **

Non-ferrous metals such as aluminum, copper, and brass are not detected by a typical metal detector. This is because these metals do not have magnetic properties like ferrous metals such as iron and steel. As a result, metal detectors are not able to pick up signals from non-ferrous metals, making them undetectable by the device. **

The best metal detector will depend on your specific needs and budget. Some popular options among hobbyists and professionals include the Minelab Equinox 800, Garrett AT Pro, and Fisher F22. These models are known for their advanced features, durability, and accuracy in detecting various types of metals. It's important to research and consider factors such as the type of terrain you'll be detecting on, the types of metals you're looking for, and your level of experience before choosing the best metal detector for you. **

To make your portable air conditioner more efficient, you can start by ensuring that the unit is properly sized for the room you are trying to cool. Additionally, make sure that all windows and doors are closed to prevent cool air from escaping and warm air from entering. Regularly clean or replace the air filter to maintain optimal airflow. You can also use curtains or blinds to block out sunlight and reduce the heat load on the unit. Finally, consider using a fan to help circulate the cool air more effectively throughout the room. **

A good option for downhill mountain biking that is affordable, compact, lightweight, and portable is a folding mountain bike. These bikes are designed to be easily folded and carried, making them convenient for transportation and storage. They are also typically more affordable than traditional mountain bikes and are lightweight, making them easier to handle on downhill trails. Overall, a folding mountain bike is a great choice for those looking for a practical and versatile option for downhill biking. **