Mr. Li is awesome. Professional, knowledgeable, thorough. Purchased a provia front door and love it. Replaced an old original, ill-fitting and inefficient wood door. The door is great quality and is tightly sealed against airleaks. His team is also tidy, courteous and effiecient. Can’t say enough great things about working with Crystal Exteriors. Mr. Li took care of all the details including follow-up to see if we were satisfied. The best!