The MacBook Pro "Core i7" 3.1 13-Inch (Early 2015 Retina Display) originally was a "configure-to-order" configuration for both the MacBook Pro "Core i5" 2.7 13-Inch (Early 2015 Retina Display) and MacBook Pro "Core i5" 2.9 13-Inch (Early 2015 Retina Display), but also is documented as a separate model for reader convenience. Starting on October 27, 2016, it only is a CTO option for the MacBook Pro "Core i5" 2.7 13-Inch (Early 2015 Retina Display). The processor (and the corresponding larger level 3 cache), are the only substantial differences between this model and its stock compatriots.
The MacBook Pro "Core i7" 3.1 13-Inch (Early 2015 Retina Display) features a 14 nm "Broadwell" 3.1 GHz Intel "Core i7" processor (5557U), with dual independent processor "cores" on a single silicon chip, a 4 MB shared level 3 cache, 8 GB of onboard 1866 MHz LPDDR3 SDRAM (which could be upgraded to 16 GB at the time of purchase, but cannot be upgraded later), 128 GB, 256 GB, or 512 GB of 4 Lane PCIe-based flash storage, and an integrated Intel Iris Graphics 6100 graphics processor that shares memory with the system. It also has an integrated 720p FaceTime HD webcam, and a high-resolution LED-backlit 13.3" widescreen 2560x1600 (227 ppi) "Retina" display in a case that weighs just less than 3.5 pounds (1.58 kg). It does not have an internal optical drive.
Connectivity includes 802.11ac Wi-Fi, Bluetooth 4.0, two USB 3.0 ports, two "Thunderbolt 2" ports, an HDMI port, an audio in/out port, and an SDXC card slot.
In addition, this model has a backlit keyboard, a clever haptic-capable "Force Touch" trackpad and an internal, sealed battery that provides an Apple estimated 10 to 12 hours of battery life depending on use.