Dow XIAMETER™ RTV-4135-L Base for use with XIAMETER™ RTV Curing Agent products. SILASTIC™ L RTV Silicone Rubber is a two component, pourable silicone rubber that has superior elongation, low modulus, high strength, good part removal, minimized tear, long mold life and is capable of deep undercuts and close tolerances. Base only. 4 kg Pail.