Let and . Given an Adjunction there is a Natural Transformation such that in corresponds to in This is a dual notion to a Unit. Triangular Identities Lemma Let be an Adjunction with counit . Then is pointwise Epimorphism if and only if is Faithfull. Proof Lemma Let be an Adjunction with counit . Then is Isomorphic if and only if is Full and Faithfull. Proof