This antenna is the original Cisco 2.2dBi unit fitted to access points like the AIR-1231b/g. It's a good quality, good performing antenna. If you need one of these it's either because your regular stockist has none, or someone has pinched the antenna from your access point ;-) Don't worry this is the original replacement!
Manufacturers Description
Cisco Aironet 2.4 GHz Articulated Dipole Antenna (AIR-ANT4941)
This antenna operates in the 2.4- 2.5-GHz band and is designed for use with Cisco Aironet radio products utilizing a reverse-polarity threaded naval connector (RP-TNC).
Technical Specification
Frequency band: 2.402-2.495 GHz
Gain: 2.2 dBi
Modulation: Dipole
Antenna type: Dipole
Operating temperature range (T-T): 0 - 60 °C
Weight: 200 g