We will talk about the features to help you make the best choice for a FRS Radio. A channel is a frequency that you communicate on. The FCC has set aside 14 frequencies for FRS use. This is how a sub-channel is created. If the receiving radio is listening for the same tone that is being transmitted then it will allow the transmission to be heard.
Some manufacturers use different tones on specific sub-channels.
Review the manufacturer documentation to get the tone frequencies for each sub-channel. A keypad lock allows you to lock the keypad so you don't inadvertently change the settings of the radio. This is mainly used to prevent channel changes. If you do not have the same model the communication will unintelligible. This is a good feature to use when you want to find a free channel in a crowded area.