Flashlight parts

From top to bottom, a flashlight is normally made of these parts:

1. Bezel
2. Lens
3. Reflector (or TIR)
4. LED
5. MCPCB (board the LED is soldered to)
6. Metal heat sink (shelf or pill)
7. Driver (makes the LED get the right current and voltage)
8. Cell
9. Tail cap

1-7 are contained within the head. Number 6 is where flashlights can differ and can have either:

• A shelf that’s machined from the same block of metal as the head. This provides a great thermal path to dissipate the heat. The shelf has a hole for the wires connecting the driver to the MCPCB. You can’t remove the MCPCB or driver without desoldering the wires.
• A pill, often brass, that screws into the head. If you take the pill out, the LED, MCPCB and driver come with it too. Sometimes these 3 parts are sold together as a “light engine”, which swapped very easily.