From Halopedia, the Halo wiki
The MC5 Individual Data/Net Terminal is a TACPAD, compatible with the armor accessory Tactical/TACPAD wrist dock.
The MC5 is a terminal that can be docked into the Tactical/TACPAD wrist dock.
The MC5 was used by Carter-A259 at the tail end of the Human-Covenant War to his death.
The MC5 was also used by Hazel-A302 at her time at Outpost Discovery.
The TACPAD in Halo: Reach's armory.
A TACPAD from a first-person view in Halo: Reach.
Extracted model of the TACPAD.