I use a Robic SC-5002 which is a count down timer on a lanyard. I like it since it's not on my wrist, and can be started/stopped while still in your shirt pocket (it has a button on the front that you can easily feel thru the fabric of the pocket). It also has a low volume "beep" that lets you know that you just turned it on/off when you hit the button. Not much money, can easily change battery, and leaves hands free since you don't wear it on the wrist.
It's slightly larger that a baseball ball/strike counter with an easily readable large character display.
http://www.amazon.com/gp/product/B00...ance&n=3375251