Here are the differences between the Braun BT420 and the Braun BT240 beard trimmer: The BT420 has a longer battery life of 60 minutes compared to 45 minutes for the BT240. The BT420 has 20 length settings, while the BT240 only has 17. The BT420's cutting lengths range from 0.5 mm to 10 mm, while the BT240's range from 1 mm to 10 mm. The BT420 has a cutting width of 32 mm, while the BT240 has a cutting width of 30 mm.

100 - 240 volts

There is no USB cable, but there is a mains charger. The shaver has a battery that lasts a relatively long time.

I meant 10mm