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I need a Power Injector for a Cisco 521 Wireless Express Access Point. What is the P/N, AIR-PWRINJ3 or AIR-PWRINJ4? Or 802.3af at switch only?
This one should work for the AP 521;
IEEE 802.3af - Cisco Aironet Power Injector
Hope this helps!
AIR-PWRINJ3 doesn't support 802.3af standard, only Cisco pre-standard inline power.