  Recently the superconducting gap functions of the skutterudite
PrOs$_4$Sb$_{12}$ have been proposed [K. Maki et al, Europhys. Lett. {\bf 68},
720 (2004)]. The superconductivity is spin-triplet and consists of at least 2
distinct phases in a magnetic field, which bears some resemblance to superfluid
$ ^{3}$He. Here we present our analysis of the thermodynamic properties of
these two superconducting states within the weak-coupling BCS theory. The
superfluid density of the B phase is compared with recent experimental data.
