High quality decompression connecting rod:Inside is a rigid steel tube,Wrapped with high-quality foam on the outside to reduce pressure and slip Stable lock: Threaded ends with star-lock collars provide a safe, secure workout and easy weight plate changes Multi-function:You can freely combine dumbbells of different weights according to your exercise method.It can also be used as a barbell by connecting rod Great choice:Dumbbell is ideal for various warm ups sports and strength workouts like arms, shoulder, abdominal, legs or back training Note: The Options only suit for aperture 1 inch /2.6cm weight plate (The Dumbbell not include.) Weight Limit: Bar 20lbs ;Barbell Extender 40lbs