Smitty1001, Precisely. One end goes in place of your BVM check valve and stays with plane as your NEW check valve, other end stays with compressor, that way you just click the to connect, fill up, then unclick them. ZERO air lost during "unclicking" process and no having to thread and unthread fill valve.
Its just cleaner and easier, just like DelGatoGrande shows in his photo.