This is a mount, for mounting a TP-Link TL-WR841n(d) router on its power supply, so you can mount it on a wall without drilling holes. The router is pretty lightweight, so this should work fine. However, I am not responsible for any damage on your devices or wall outlets.
You will need:
6x M3 nuts (maybe 4 of them should be lock nuts)
2x M3 x 15 screws (countersunk or flat cylinder head)
2x M3 x 30 screws (countersunk)
some spacers like silicone pads or something else for clamping the PSU (there is 2-3mm space left to be compensated)
And of course your WR841n and its PSU.