G.F. Sprague & Co. Inc. is Sharon Ma's replacement window contractor. Whether you have aluminum windows, or vinyl windows, we have the replacement window option for you. All of our work is backed up with a 40 year handiwork warranty. So you have self-confidence with GF Sprague with all your work for replacement windows. G.F. Sprague has been in company since 1969 and has more than 10,000 satisfied consumers.