LabSat 4 units are compatible with 2 file types from the LabSat product ranges; LabSat 3 Wideband (*.ls3w) and LabSat 4 (*.ls4).
If you require your LabSat 4 unit to play a scenario file recorded on any other LabSat version, you can use the LabSat Scenario Converter software. You can download this software from the LabSat website and use it to convert most LabSat files from the various LabSat versions to a file type that is compatible with your unit. It will also let you convert files in bulk.
You can find more information about how to use the LabSat Scenario Converter and its limitations here.