Bought this item to set display so that it would always show the last 7 to 9 days of rainfall. Sorry about that! The only way to get the last 7 days is to either remember to re-set the cumulative display every 7 days OR to select each previous of the last 7 days and then manually ADD UP the rainfall for 7 days...UNACCEPTABLE!Also there are TOO MANY little screws that have to be removed in order to change batteries....about 9-10 if I remember correctly.Sent this unit back and bought Honeywell TC-152. It is cheaper and can be set to always display last seven days of rainfall. Down side...it has a lot of screws to remove also.