The SLS Block 1 vehicle uses the ICPS as its in-space second stage. The ICPS is a variant of ULA’s (United Launch Alliance) DCSS (Delta Cryogenic Second Stage) with some customizations.

SLS will debut with an uncrewed Orion spacecraft on EM-1 in its Block 1 configuration, which has an ICPS upper stage stacked on top of its foundational elements of two five-segment Solid Rocket ...