M.2 stands for Next Generation Form Factor which is invented for PCI-SIG by Intel and it is developed for flat and high-efficiency equipment such as Ultrabook™ or Tablet PCs. It is a natural transition from the Mini Card and Half Mini Card to a smaller form factor in both size and volume which supports multiple function add-in cards/modules including: Wi-Fi, Bluetooth, global navigation satellite systems, near field communication, Hybrid digital radio, wireless gigabit alliance (WiGig), wireless wide area network and solid-state storage devices. Also adds functionality to USB 3.0, display Port, SDIO and SSD-PCIe

The P15S-P15F adapter is designed for desktop/Laptop PCs that convert mini PCI-E cards.
 You can insert your USB or PCIe-e type minicard to this adapter.. Also, WiFi& Bluetooth Combo card such as Intel® Dual Band Wireless-AC 7260 can be used for supporting both WiFi by PCIe and Bluetooth by USB at the same time.