We have road tested a few clickers after one of our dogs was very sensitive to a loud 'click' and these were a favourite. In six bright 'hard to lose' colours with a bungee wrist bracelet, you will find it hard to misplace these clickers! 
As far as design and ergonomics are concerned, we also found this Clicker sits easily in your hand with no hard edges. 
An all-around great clicker and a good choice for noise-sensitive dogs. 
Why Click? 
Clickers, are used to mark that moment in time where you want your dog to know he has got it right, and it offers a couple of advantages over using your voice to mark when they been successful.
Clickers are more precise – using a click when you see that behaviour you are looking for is an accurate way to reinforce your dog/cat/sheep/horse/alpaca/husband. (just kidding, husbands are not always open to clicker training!)
Clickers offer a consistent tone – Clickers sound the same every time, unlike the sound of your voice which can change depending on your mood, whether you have a cold or even time of day.
Is Clicker Training essential to training my dog?
We think that no matter whether you feel you will not use a clicker for every training session, you will become a better trainer by becoming proficient in using a clicker. For this reason alone every dog owner should have a clicker in their kit.
Some research indicates that using a clicker speeds learning for your dog. However, good 'marking' with your voice is effective too, we just think you will become better at using your voice if you become skilling in using the clicker.
To look at how to use a clicker: https://www.youtube.com/watch?v=yvw2bcGcoDk

Clickers - Light to carry with a soft click.