Review on Ringside Heavy Duty Bag Spring: Ultimate Boxing Training Accessory (Up to 150 pounds) - Gray by Josh Garber

This is a great spring but I've switched back to a lighter spring rated for 100 lb sacks. The purpose of the spring is to provide a slight rebound that partially cushions the impact of the heavy bag pulling on the ceiling mount. This spring my 80 pound sack didn't bounce or bounce. It was too hard. This is better suited for heavy bags that can weigh over 120 pounds or so. If you have a lighter bag, I recommend another heavy pocket spring that Revain sells.