The standard communications system of Starfleet crew since the late 2290s, the communicator badge provides a realtime voice/data link over subspace with the user's assigned post. Calls can also be made badge-to-badge in the absence of a spacecraft or station nearby, as the little devices carry enough power to operate themselves and their attached uniform indefinitely. Computing power inside each device is sufficient to establish and maintain a mesh network, handle call routing, and process voice input.
The wristlight is the logical evolution of Starfleet's previous portable luminance sources. A very bright LED light source with power provided from the user's wrist tricorder, it can throw a one-meter circle of daylight wherever the user points. Understandably a useful thing to have for any away team or repair crew.
Marines traditionally equip one of these over their uniform for away team missions. The tactical harness contains pockets for magazines and batteries, as well as a Type-2 quick-draw holster and a small shield generator.