  We explore the possibility of utilizing the prompt muon fluxes at very high
energies in order to discriminate various models/parametrizations of low-x QCD
behaviour of hadronic cross-sections relevant at such energies. We find that
the pair meter technique for measuring high energy prompt muons can be very
efficient in such an endeavor. As a by product, it allows to cleanly probe the
change in composition of the primary cosmic rays expected at high energies.
