Mega Mass Pump Pre-Workout contains everything you need to maximize the blood flow during intense workouts. The powder is free from caffeine and other stimulants, which makes it the perfect Pre-Workout for anyone that is sensitive to caffeine or wants to train in the later hours. Besides containing the key amino acids L-Citrulline and L-Arginine, Weider Mega Mass Pump also features a comprehensive blend of plant extracts that can help to regulate vasodilation (widening of the blood vessels).