The HPP-28756-25SK is the part number we use for the seal kit that we created that contains the inner and outer piston lip seal used in the Sonnax 28756-25K. Sonnax sells the two seals individually and we have simply combined them into a single kit. We purchase the individual seals directly from Sonnax.
Our HPP-28756-25SK kits include one inner and one outer piston lip seal.
