Other than shoes, this is my only must-have running item. Before I got this belt, I had to carry my keys and phone in my hands. This belt (a small fanny pack really) has two compartments that are just right. The smaller compartment is a perfect fit for keys and the larger is perfect for a phone. The zipper provides easier access to a phone than armbands or other phone holders. It's easy to take the phone out to change podcasts or check distances or maps.
The belt is easily adjustable and comfortable to wear. I don't go running without it.