Asus RS100-E4/PI2 - Manual (Page 38)

Chapter 3: Installation options 3-4
2. Attach the inner rail to the correspoding side of the chassis and secure
with three inner rail screws. Make sure the rail is oriented as shown.
3. Attach the second inner rail to the other side of the chassis and secure
with three inner rail screws.
4. Select one unit of space (1U) on
the rack where you wish to install
the server.
5. Place three (3) nuts on the front
and three at the back. Do the
same to the corresponding side
of the rack.
Nuts
6. Adjust the length of the outer
rail to fit the length of the rack
cabinet then fasten the two
screws.