Serious Mass by Optimum Nutrition (ON) is a high-protein, high-calorie mass gainer designed to help you bulk up quickly and effectively. It’s ideal for those struggling to gain weight, athletes, and bodybuilders looking to increase muscle mass.

• ⚡ 1,243 Calories per serving

• 💪 50g Protein

• 🥔 254g Carbohydrates

• 🍫 Flavor: Chocolate

• 📦 Net Wt: 1kg / 2.2 lbs

• ✅ Supports muscle building & recovery

• 🔒 ON Tru Seal – 100% Authenticity Verified

Form: Powder
Goal: Weight gain, muscle mass, calorie boost