HIGH QUALITY: Made of durable cast iron, weights are covered with a durable, floor friendly plastic covering 2 IN 1 DESIGN: Free connection steel tube to change dumbbell to barbell, it not only burns calories, but improves muscle strength, muscular endurance and heart health ANTI-SLIP: Threaded collars for securing plates to barbells; textured grips promote secure, comfortable hold WIDELEY APPLICATION: Dumbbells can help you improve cardiovascular fitness, burn calories, free weights, build muscle or increase muscular endurance for sports Note : The difference between 1 and 2 is only the difference between whether there is a connecting rod, 1 without a connecting rod is just a dumbbell, and 2 has a connecting rod, and the dumbbell can be converted into a barbell through the connecting rod. Please choose according to your needs, thank you. Package List: DE-TJ05396-1 2pcs x 1kg weights plate 2pcs x 2.5kg weights plate 4pcs x 3kg weights plate DE-TJ05396-2 2pcs x 1kg weights plate 2pcs x 2.5kg weights plate 4pcs x 3kg weights plate 1pcs x connection steel rod