Tags may be selected for compliance with certain standards. The standards may be open, such as ISO, or they may be proprietary. It is a good practice to follow the open and popular standards, because more companies manufacturing products use these standards than proprietary ones, providing a wider choice of products. In addition, these products may be cheaper due to higher volume, and support for them may be available for a longer period. With the wide acceptance of EPC Gen 2 standards (now also ISO 18000-6c), it is best to use Gen 2–compliant products if you are going to use UHF tags.