Acer Altos G900 User Manual page 173

1 Extend the inner rail out of the rail assembly until the component
rail release latch clicks. Hold down the latch and slide out the
inner rail out of the rail assembly. Do the same thing to the other
assembly rail.
2 Install the outer rails to the rack.
Figure 66 - Sliding out the inner rails
Figure 67 - Installing the outer rails to the rack
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