G.F.Sprague & Co. Inc. is Boston Ma's replacement window contractor. Whether you have aluminum windows, or vinyl windows, we have the replacement window solution for you. All of our work is backed up with a 40 year workmanship warranty. So you have confidence with GF Sprague with all your work for replacement windows. G.F. Sprague has been in business since 1969 and has over 10,000 satisfied customers.