These are programmed NFC tags that can be used in an XYZ Printing 3D printer. They have been tested in a Da Vinci Jr. and Mini 3D printer. You get 20 tags. They can be programmed for 190, 200, and 210 degree temperatures. Once you complete your purchase please message me and tell me what temperatures you want. You can mix and match or get them all programmed for one temperature.