If you have the money, cause they are more expensive than Chrony's, get an Oehler! ive had a model 11 for over 25 years, and a model 33 for about 20 years. flawless performance, and best warranty in the business. and Dr. Oehler is a fantastic guy, full of info. He builds chronos for the military, so good enuff for them, good enuff for us.