The iMac Core i7 3.3 21.5-Inch Aluminum (Retina 4K, Late 2015/Broadwell) technically is a configure-to-order configuration of the iMac Core i5 3.1 21.5-Inch Aluminum (Retina 4K, Late 2015/Broadwell), but also is documented as a separate model for reader convenience. Other than processor (and the corresponding level 3 cache), these two models are identical. The iMac Core i7 3.3 21.5-Inch Aluminum (Retina 4K, Late 2015/Broadwell) features a 14-nm Broadwell Quad Core 3.3 GHz Intel Core i7 processor (5775R) with four independent processor cores on a single chip, a 6 MB shared level 3 cache, 8 GB of onboard 1867 MHz LPDDR3 SDRAM (which could be upgraded to 16 GB at the time of order, but cannot be upgraded after system purchase at all) , a 1 TB (5400 RPM) hard drive, and an integrated Intel Iris Pro 6200 graphics processor that shares system memory. 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 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 2 ports, Gigabit Ethernet, 802.11ac Wi-Fi (802.11a/b/g/n compatible), and Bluetooth 4.0. Specifications Make & Model - Apple iMac 21.5 Late 2015 Form Factor - All in One Processor - Intel Core i5 5775r 3.3Ghz Ram - 16Gb Hard Drive - 512Gb Hard Drive Type - SSD Connectivity - USB Ports: 4 (3.0) + 2 x Thunderbolt Display - 21.5 LED-backlit 16:9 widescreen TFT active matrix Retina 4K display with IPS technology, a native resolution of 4096x2304 Optical Drive - Nil Network - Gigabit Ethernet, 802.11ac Wi-Fi (802.11a/b/g/n compatible), and Bluetooth 4.0 Operating System - Mac OSX Condition - Refurbished Grade A Whats Included - PC + Power Cable/ Adapter Warranty - 6 Months All parts are original unless specified otherwise