These rechargeable batteries can be used with your Echo transmitters by inserting them into the Battery Cartridge (p/n UM2000130). When running in normal everyday drilling conditions, these rechargeable batteries are a great choice. Run them for a couple days and switch out to the second battery while the other is recharging, saving time and money.  Our chargers may be used with 110v outlets or in your truck via a 12v outlet (see p/n UM1040230).