Facial Serums Beauty & Personal Care, Face, kNutek, Skin Care, Treatments & Masks A-RO Balsam Serum for Acne and Rosacea by kNutek – 4oz Review by WaxHydra May 31, 2018 No Comments 4 oz (120 ml) container. More A-RO Balsam Serum for Acne & Rosacea is an incredible solution only available from kNutek.