i have 4, but, they are identical to each other. Each of my clickers are attached to coil-bracelet keychains, so i can wear them on my wrist when training.
and i so agree 100% with Sara, who was one of the ppl who helped talk me into trying a clicker, years ago, and oh wow, yes, she was right, a "click" really helps mark a correct behavior to a dog much faster that a "good boy" does. Plus, one can be so so so much more precise with a click, than i can be with "good boy" or "yes".
My dog also hears "good boy" several times a day fairly randomly, it's less powerful to my dog.
Clicker training is also how they train the killer whales at SeaWorld, and most circus animals, too. If you haven't tried one, do at least try one, you might be surprised like i was, at how much faster a dog "gets it" when you use a clicker.
The very sight of the clicker, makes my dog "come alive" and "put on his thinking cap". He gets very very very tail-waggy if i take the clicker out of the drawer.