The wired product is the most effective. All ranges with Lithium-Ion are a real ruin for the wallet. The batteries cost a huge price and the charger goes with also ... A cord is not so troublesome than that. You really have a mad distance to be bothered by a cable. Finally, with a wired power is still there. The battery has a power that is not continuous, it is not just a big capacitor that discharges ... and after a good 1 / 4h, the power is gone. WIRED = EFFECTIVE! :-)