you just need to decide if you want the digital or the analog. And if you want the analog I think you want the second version which doesn't need the cap left on to save the battery. I first got a new analog and used it for 10 years and it never failed but it got lifted out of my car, so I bought a used digital and have continued to use it for 24 years though I think it might be miss reading a bit now. I prefer the digital for the reason that it fits in my pocket better.