LED power indicator and a built-in fuse for additional safety. I got this Sakura power inverter for about a year now and probably only used it 3x. It does work, but only plug it in if your car is on, because it will drain the battery of your car quickly when you plug it in without starting your car.
Product description from the manufacturer:
Use your electrical appliances on the go thanks to the Sakura 12V Power Inverter. Simply plug the Sakura 12V Power Inverter into your 12V car cigarette lighter socket to convert your vehicle's battery power to 240V mains.
It negates need for separate costly in-car chargers for electrical products but allowing you to charge and use them using their normal everyday mains adapter. It is a simple device with a multi-angle head that plugs into the cars 12V socket & provides you with a 3 pin household socket allowing you charge any device up to 80W including laptops, PDA, game console, mobile phones, MP3 players and even TVs.