OptiCulture™ Serum-Free Medium-B (4E3-500-B) is designed for CNS and retinal research, providing a nutrient-rich, physiologically attuned environment that supports cellular health, barrier integrity, and functional phenotype expression. This kit includes 500 mL basal medium, OptiBoom-B (brain-derived growth factors), additional supplements (ITS, Anti-Oxidants, Hydrocortisone), and 10 mL Attachment Factor for coating flasks. 4E3-500-B is certified for experimental use, phenol-red free, and contains no added hormones or antibiotics. Ideal for barrier models, neurovascular unit systems, organoids, co-cultures, disease modeling, and drug screening.