We have a new 3000 sf home, supposedly with NAPCO vinyl windows. Fit and travel are OK, but HORRENDOUS problem with sweating. Have not yet spoken with our contractor, among other things, to see if these are NAPCO. Last nights temp was 45F, and every window in the house sweated! This despite central air, and running bathroom fans 30 min. after each shower. These are NEW, not replacement. I might advise you to RUN away from NAPCO!