Optimum Nutrition Serious Mass Vanilla 5.45kg. A calorie rich protein source. Protein Powder High Calorie Mass Gainer with Vitamins, Creatine and Glutamine. Supports muscle building and weight gaining. More than 1260 kcal per serving to help boost your calorie intake. 50 g protein per serving to help build and maintain muscle. More than 250 g carbohydrates per serving to help support muscle Recovery