Master Series Ass Relax Desensitizing Lubricant 4.25 oz. Reward them with a little understanding. Ass Relax Anal Desensitizer helps ease the potential discomfort associated with anal play. This silken liquid glides on seamlessly, creating a light numbing effect, keeping your partner comfortable so you can master their pleasure. Size: 4.25 fluid ounces. Active ingredient: Lidocaine.