There is a fuel gauge.
According to Jetbeam's description, the display can show either the brightness level or remaining battery power (i.e. fuel gauge). The pics above show "8" on the screen and since there are only 3 brightness levels, it must be showing remaining battery power.
Quote from CPF Marketplace:
Product Feature:
- Adopts 3* Cree U3 LEDs, Max 3200 lumens
- Advanced digital display system, under the patent protection.
- Display output mode
- Display battery power
- Easily operation of side control switch
- Rechargeable design
- Waterproof to IPX-8
Function Parameters:
1. Light source: 3*Cree U2 LED
2. Battery: 3*18650
3. Output & Runtime:
Function High Middle Low Strobe
Output 3200 LUMENS 500 LUMENS 30LUMENS 3200 LUMENS
Runtime 2.5h 10h 60h
Beam distance 450m
Intensity 45000cd
Waterproof IPX-8
4. Output regulation: Side switch
5. Circuit design: Constant current circuit, constant brightness.
6 . Working voltage: 9-19V
7. Waterproof: IPX-8
8. Body: Aerospace aluminum
9. Dimension: 164 mm (L ) x 67mm(D), weight: 186 gram
End quote
On a different subject, the recharger can only be used at 15V in - I guess this means it can only be plugged into a car rather than standard wall socket.