The term split tones refers to the ability of the radio to assign a CTCSS tone or DCS code for receive and a different one for transmit on the same channel. For example, if the repeater requires a tone of 88.5 to receive and 114.8 to transmit, you would need to be able to configure your radio to transmit and receive on those tones. Most consumer grade GMRS radios only allow you to set a single tone for the channel. But a few professional grade GMRS transceivers are capable of split tones. One is the Wouxun KG-805G, which is one of the reasons why it has become so popular so quickly.
Keep in mind there are a lot of repeaters that use the same tone or code for both transmit and receive, so if you have access to one, it’s not an issue. But for those that use split tones, having a GMRS radio with this feature adds greater flexibility, especially when traveling across the country.