The iMac "Core i5" 2.7 21.5-Inch Aluminum (Late 2013/Haswell) features a 22 nm "Haswell/Crystalwell" Quad Core 2.7 GHz Intel "Core i5" (4570R) processor with four independent processor cores on a single chip, a 4 MB shared level 3 cache, 8 GB of 1600 MHz DDR3 SDRAM (which is not intended to be upgraded after purchase), a 1 TB (5400 RPM) hard drive, and an "integrated" Intel Iris Pro 5200 graphics processor with 128 MB of "Crystalwell" embedded DRAM (and shared system 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, 802.11ac Wi-Fi (802.11a/b/g/n compatible), and Bluetooth 4.0.
Compared to its predecessor, this model essentially has the same external enclosure, but it has a much more efficient "Fourth Generation" processor and architecture, as well as faster graphics, faster Wi-Fi, and the option of faster storage.