The product you've listed, the Optimum Nutrition (ON) Serious Mass Weight Gaining Powder, 907G (or 1KG/2.2 lbs), is the ultimate high-calorie supplement designed for weight gain and muscle building.1The 907g (or 1kg) jar is typically the smallest size available, offering a great way to try out the product or for travel.? Serious Mass: Key Features & NutritionSerious Mass is one of the most recognized supplements for individuals known as "hardgainers"—those who struggle to consume enough calories and nutrients to increase their body mass.2ComponentAmount Per Full Serving (2 Scoops in Water)Key FunctionCaloriesOver 1,250 KCAL (increases to $\approx$ 1,640 KCAL when mixed with low-fat milk)Provides a massive caloric surplus essential for weight gain.Protein50 Grams (Blend of Whey, Caseinate, and Egg Protein)Supports muscle recovery, repair, and growth.Carbohydrates250+ Grams (Primarily Maltodextrin, often with No Added Sugar claim)Replenishes glycogen stores after intense training and drives the high-calorie count.Creatine Monohydrate3 Grams (or 5 grams in some regional formulas)Helps increase muscle strength, power, and size.Micronutrients25 Essential Vitamins & MineralsSupports overall bodily health and helps the body process the large intake of nutrients.