I have 7 Sigmas. They all work fine, 6 have been in the rain. They all have replaceable batteries. The oldest one is from around
1999 it has over 10,00 miles on it in 15 years, never a problem. I get a few years from each battery. Never counted the years.

The two newest ones mate to a docking station that feeds the data to my lap top. It stores data, will compare rides, and lets you map your ride.