This iMac is in good shape and runs great! 

May show sings of wear (please refer to pictures).

This model is powered by a 14 nm, 64-bit "Seventh Generation" Intel Core i5 "Kaby Lake" (I5-7400) processor which includes four independent processor "cores" on a single silicon chip. Each core has a dedicated 256k level 2 cache, shares 6 MB of level 3 cache, and has an integrated memory controller (dual channel).

This system also supports "Turbo Boost 2.0" -- which "automatically increases the speed of the active cores" to improve performance when needed (up to 3.5 GHz for this model).

This model has an AMD Radeon Pro 555 graphics processor with 2 GB of dedicated VRAM.

This model has a 21.5" LED-backlit 16:9 widescreen TFT active matrix "Retina 4K" display with IPS technology, a native resolution of 4096x2304, a "wide color" DCI-P3 gamut, and brightness of 500 nits. By default, it runs "pixel doubled" at 2048x1152, but also can run at scaled resolutions of 2304x1296 and 1560x1440.

This model can simultaneously support the internal display at full native resolution and up to one 5120x2880 (5K) external display at 60 Hz with support for one billion colors; two 3840x2160 (4K UHD) external displays at 60 Hz with support for one billion colors; or two 4096x2304 (4K) external displays at 60 Hz with support for millions of colors. It supports both extended desktop (second workspace) and video mirroring (internal display duplicated on the external display) modes.