PCI Express 3.0 x16 interface, compatible with PCI Express x8 and x16 slots, support data transfer rates up to 128 Gbps.

Up to 4 x M.2 slots (Key M), type 2242/2260/2280/22110 (supports PCIe 3.0)*
* Supports PCIe M.2 storage devices only. Maximum SSDs support will vary, depends on different motherboard´s design.

1 x M.2 FAN Power Switch
4 x M.2 access LEDs

RAID function Support on ASUS motherboards:
Intel® RAID on CPU function ready for some X299, Z370 and Z390 Series Motherboard models. (It supports Intel® SSDs only.)

AMD® X399/X470/B450/X370/B350/X570/TRX40 Series Motherboard models*

* Maximum number of M.2 SSD support will vary, it depends on different CPU specs and PCIe bifurcation settings in different ASUS motherboards.
Please see the FAQ link for full compatible lists and further information:
https://www.asus.com/support/FAQ/1037507

20.2 * 9.6 *1.3cm