D-Link Xtreme N Duo DAP-1522 User Manual page 21

Section  - Configuration
For WEP encryption, enter a Network Key exactly 5 or
13 characters long or exactly 10 or 26 characters using
0-9 and A-F.
Click Next to continue.
If you select WEP encryption, the following screen will
show you your network key to enter on your wireless
clients.
Click Save to finish the Setup Wizard.
D-Link DAP-15 User Manual 1