  Let $\mathcal{S}$ be a class of finitely presented $R$-modules such that
$R\in \mathcal{S}$ and $\mathcal{S}$ has a subset $\mathcal{S}^*,$ with the
property that for any $U\in \mathcal{S}$ there is a $U^*\in \mathcal{S}^*$ with
$U^*\cong U.$ We show that the class of $\mathcal{S}$-pure injective
$R$-modules is preenveloping. As an application, we deduce that the left global
$\mathcal{S}$-pure projective dimension of $R$ is equal to its left global
$\mathcal{S}$-pure injective dimension. As our main result, we prove that, in
fact, the class of $\mathcal{S}$-pure injective $R$-modules is enveloping.
