I recently purchased this pedometer used. I am selling it because it doesn't have the features I want, so I haven't used it much. There are no noticeable stains or marks. Pairing with a smartphone has been解除済み. When I put in the battery, a dotted square (indicating a poor battery connection or low battery) appeared, but it didn't seem to be a connection issue. The battery had just been replaced, so I set it up according to the instructions, and it worked without any problems. I will ship it with the battery removed.