Medium size vinyl coated polyester outer bag with one ballistic nylon filler bag for a great variety of sandbag training exercises. Fully filled, holds up to 100 pounds ( 45 kg ) of sand. But, it can be under-filled to allow for an even greater variety of moves, or for female athletes. And, you have the added option of purchasing another filler bag to cut the sand load in half. That way, you can have an outer bag holding up to 50 pounds and 100 pounds, depending upon whether you use one or both filler bags. Our bags were designed to deliver a better sandbag training experience. They do this by allowing the entire sand load to shift as a whole with the outer bag. Here's to your sandbag training success! You will be happy with your Workout Sandbags!