The MagSafe connector pins are palindromic, allowing for the adapter to be inserted in two opposite orientations. The first and second pins on each side of the tiny central pin have continuity with their mirror pins.

* The inner large pins are V+ (16.5 VDC). Measuring with no load will give 6.86 VDC; the full 16.5 V is provided to the proper load.

* The outer large pins are Ground.

* The tiny center pin is a Charge Control pin that assists with changing the LED color, and also assists with switching the adapter off. No power will be output from any of the other pins until contact is made with the center Charge Control pin. This pin is also used to transfer additional Information, such as the powertype and serialnumber of the powersupply.

The rectangular metal shroud surrounding the pins has no electrical function. Rather it acts as shielding for the electrical pins and a ferrous attractor for the magnet in the laptop.