This is new technology--a rechargeable magnetic beacon. Now you can operate a magnetically mounted beacon without having to run a cable out the window. The unit has an integral on/off switch with a smart battery status LED indicator and a combined magnet and suction cup mounting.
 

Light source: 12 x 3W 3535 high power LEDs
3 flash patterns—single flash, dual flash, rotate
Integral on/off switch and smart battery status LED indicator
Comes with 12-24V cigarette plug and 240V wall socket chargers
E-approved to ECE R65 when running from external power
Battery: 18650 li-ion battery, 7.4V/2200MA
Charging voltage: 12-24V DC or 240V AC
Charging Time: 3 hours
Run time: 3 hours
Waterproof rating: IP65
Mounting: Combined magnet and suction cup
Size: 140mm (h), 128 mm (dia)
Charging cable stretches to maximum length of 3 metres
Not for high speed operation. 100kmh max vehicle speed