Very poor communication with the store. The tachometer works, but will only work until the battery is discharged, because it can not be replaced or charged, so when discharging the tachometer battery, you can throw it away. The merchant did not answer this question at all, pretending not to understand issue regarding battery discharge. So if you plan to use it for about 1 year, then OK and then buy a new one again
The package I did not age properly I received a refund