This bundle is trivial, but its different trivializations Q = R × × M correspond to the choice of different non-relativistic reference frames. Such a reference frame also is represented by a connection Γ Γ on Q → → R which takes a form Γ Γ i = 0 with respect to this trivialization. The corresponding covariant differential ( q t i − − Γ Γ i ) ∂ ∂ i determines the relative velocity with respect to a reference frame Γ Γ .