What are adjustable dumbbells?
Adjustable dumbbells allow you to add/remove weight plates from a single dumbbell's handle to change between weight resistances. The least expensive style uses clips or collars (ex. spinlock) that are removed manually to switch weights, and the other, known as selectorized, offers a more automated pin and/or dial adjustment system. Adjustable dumbbells are space savers since you can have multiple dumbbells in just one set, and they can also be more cost effective than fixed-weight sets depending on how many weight resistances you want to have. However, there are some drawbacks. Adjustable dumbbells with a manual adjustment system can be slow and cumbersome when you need to switch weights and so they aren't ideal for speed circuits. Additionally, adjustable dumbbells (especially the inexpensive ones) aren't considered to be as safe during heavy lifting sessions as a fixed-weight dumbbell would be. This is because it is possible for locking mechanisms on the weight plates to start to loosen over time and the plates could fall off of the handle.