The first example of SPT order is the Haldane phase of odd-integer spin chain. It is a SPT phase protected by SO(3) spin rotation symmetry. Note that Haldane phases of even-integer-spin chain do not have SPT order. A more well known example of SPT order is the topological insulator of non-interacting fermions, a SPT phase protected by U(1) and time reversal symmetry.