The iMac "Core i5" 2.7 21.5-Inch Aluminum (Late 2012) features 
a 22 nm Quad Core 2.7 GHz Intel "Core i5" I5-3335S (Ivy Bridge) processor with 
four independent processor cores on a single chip, 
a 6 MB shared level 3 cache, 
8 GB of 1600 MHz DDR3 SDRAM (which is not intended to be upgraded after purchase), a 1TB HDD, and
a NVIDIA GeForce GT 640M graphics processor 
with 512 MB of dedicated GDDR5 memory. 

It also has a built-in "FaceTime HD" webcam and stereo speakers, but lacks an optical drive.

This model has a 21.5" 1920x1080 LED-backlit 16:9 widescreen IPS display with the "cover glass fully laminated to the LCD and anti-reflective coating." 

The rear of the case is aluminum and is thicker in the middle and tapers to a razor thin 5 mm at the edges.

Connectivity includes: 
four USB 3.0 ports, 
dual Thunderbolt ports, 
Gigabit Ethernet, 
802.11n, and 
Bluetooth 4.0

Please note that stock images are used.