The USP-S | Serum is a Classified-tier pistol finish in Counter-Strike 2, originally introduced as part of The Arms Deal 2 Collection when the CS:GO Weapon Case 2 launched in September 2013.

The float range for this finish is restricted to 0.00–0.25, so Factory New, Minimal Wear, and Field-Tested are the only obtainable conditions on the open market. Battle-Scarred examples are not produced, so the most worn copies still retain a relatively clean appearance.

A StatTrak™ version is available, which tracks confirmed kills made while the skin is equipped and typically commands a premium over the standard finish. Active listings for USP-S | Serum are tracked across 17 marketplaces, with prices spanning $48.22 to $585.69 depending on wear, variant, and seller.