Why choose our weightlifting vest system: Our 6 specialized vests (8 pounds, 12 pounds, 16 pounds, 20 pounds, 30 pounds, 40 pounds) use patented underarm lock technology to eliminate bounce and falls, aiming to solve the top problem in weight training - vest slip during explosive movements. Unlike the one size fits all adjustable vest, each precise weighted model provides optimized balance for specific fitness goals. Breakthrough anti slip technology: ? Underarm locking professional system: During sprinting/burping, the ratchet style armpit buckle can be tightened with one pull -100% anti slip tested in the laboratory Gender adaptive contour: Women's Ergo Fit: Narrow shoulder straps+curved chest board. Men's Power Frame: Strengthen lumbar support+widen shoulders. ? Zero bounce project: 360 ° weight dispersion to prevent swinging during box jumping or pull-up ? High quality fabric without odor: ready to use upon opening, no need to worry about odor impact. ? Multi functional storage: convenient for storing mobile phones, keys, water bottles and other personal items, allowing you to free up your hands for exercise.