This stand add some additional degrees of tilt to your MX Ergo for extra comfort.
The gray one has 10 degrees of tilt, just like the one included with the MX Ergo
...Plus Plus.
The black version has 15°.
I highly recommend to stick some rubber or anything under it to get an extra grip as plastic can be really slippy. I personally use some cheap suede like fabric, which provide me all the grip I need.
