Most applications require tags that have both read and write capabilities so EPC Global implemented the Class 1, Gen2 air interface protocol. Gen2 tags are readable, writable passive tags that are programmed by the customer and may be locked. Gen2 is the start of a global standard for RFID communication between tags and readers. Countries control what frequency of the UHF band is used; i.e. US is 902-928 MHz, EU is 860 MHz, etc. The industry and various countries are working to harmonize onto the US approved band. Most inlays are tuned to work in all Gen 2 approved frequencies.