SPF 1138 was a type of sunscreen created by Twin Suns, and was the only type used by Sith Lords such as Darth Sidious. While vacationing on Scarif with his apprentice Darth Vader, Sidious commanded Vader to apply SPF 1138 to his back, as his shoulders had burned in the sun. Sidious also used SPF 1138 on another occasion on Naboo.
SPF 1138 first appeared in LEGO Star Wars Summer Vacation and was identified in a post by the Star Wars Twitter account.