The iMac "Core i5" 3.4 21.5-Inch Aluminum (Retina 4K, Mid-2017/Kaby Lake) features a 14-nm "Kaby Lake" 3.4 GHz Intel "Core i5" processor (7500) with four independent processor "cores" on a single chip, a 6 MB shared level 3 cache, 8 GB of 2400 MHz DDR4 SDRAM that is reportedly onboard -- but actually can be upgraded later -- a 1 TB Hard Drive+SSD "Fusion" drive, and a Radeon Pro 560 graphics processor with 4 GB of dedicated VRAM. It also has a built-in "FaceTime HD" webcam and stereo speakers.

This model has a 21.5" 4096x2304 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 4K" display (that runs "pixel doubled" to look like 2048x1152). 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 3 (USB-C) ports, Gigabit Ethernet, 802.11ac Wi-Fi, and Bluetooth 4.2.

Compared to its predecessor, this model essentially has the same external enclosure, but it has a more advanced processor and architecture as well as dedicated graphics, a brighter display, and Thunderbolt 3 (USB-C) ports.

By default, the "Mid-2017" iMac models shipped with a compact aluminum Apple Magic Keyboard and the multi-touch "Magic Mouse 2". For an additional US$30, you could upgrade from the default keyboard to the "Magic Keyboard with Numeric Keypad" and for an additional US$50, you also could upgrade from the Magic Mouse 2 to the "Magic Trackpad 2," which provides multi-touch and pressure-sensitive "Force Touch" capabilities.