PhD Aluminium Shaker is a great alternative to your plastic shaker cups. It is strong, reliable and is perfect for prolonged usage. It has a tough flip open lid that effectively prevents any kind of leakage in your gym bags.
PhD Aluminium Shaker is more durable than plastic shakers and has a flip open lid that fits tightly to prevent any leakage. Note that this can be used for cold drinks only and is a perfect shaker for prolonged usage.