Where do you buy replacement wood slats for outdoor bench?

Most slats are 4 feet long by 2.75 inches wide by 3/4 thick,( unless you have a 5 foot bench, in which case they would be 5 feet long), Home Depot or your local lumber yard would have these...at some places they could cut them for you. All you might have to do fancy would be to round off the front edge of the slat that goes at the front of the seat.