The 40LB Adjustable Cast Iron Dumbbell sets is an effective workout choice for both beginners and advanced fitness enthusiasts. This set comes with several weight plates that allow you to create several weight combinations with the dumbbells. Weights can be gradually added to this barbell dumbbell set as the workouts intensify. This 40lb dumbbell set also has spin lock collars to secure the weights in place. This dumbbell set features solid cast iron construction which can lasts for years. This adjustable dumbbell set is great for home use, as it does not require a lot of space for use or storage. This set includes: four 6lb plates, four 2.5lb plates, 2 threaded solid dumbbell handles, and 4 spin-lock collars. It is 1-inch holes fit standard sized bar.