The MIFARE DESFire 4K NXP EV3 Cards are contactless smart cards featuring authentic NXP chips that operate at a frequency of 13.56 MHz. Each card offers 4 Kbytes of memory, making them suitable for a variety of applications. These cards come in the standard CR80 credit card size (86mm x 54mm) and are sold in packs of 100. They provide an effective solution for identity verification, access control, and micropayment systems.