The 4th gen Aurora A3 has a USB-C port, metal switch, magnetic two-way clip, and a better user interface, etc. All these upgrades are based on the fact that the size keeps the same. It's still in a small keychain size with a powerful output.

Its length is 57.5mm and diameter is 15.6mm, weighs only 23.1g.

The upgraded metal switch gets clicking more comfortable and strong feedback. Regarding the user interface, it has a lockout mode and keeps the momentary-on feature.

User Interface: 

1) Lock: rapid click 5 times, the emitter blinks twice.

2) Unlock: rapid click 5 times when the light locked, the emitter blinks 3 times.

*Instant Unlock: plugged in to charge.

3) Momentary on: with the light switched off, press and hold for High mode, release the button to turn off.

4) Constant on: rapid double click to turn on from the memorized mode, then click to cycle thru moon-low-med-high; press the button for 0.5s to turn off.

*Mode memory: a mode working over 3 minutes.

5) Emergency mode: rapid triple click to turn on the strobe mode, then click to turn off.