Black. Gallon. Ultra with Biolux Technology is formulated for high fouling areas & provides excellent long-term antifouling protection. The fast dry and low VOC formula of Ultra allows your boat to be painted and launched in the same day. The addition of Biolux Technology reduces slime and increases antifouling performance for a hard durable finish with excellent color stability. Suitable water types: Sea water, fresh water and brackish water. Thinner: Brush-Ease 433.