Keystone Window of Philadelphia (Hatfield, PA)
Incompetence does not even begin to describe these morons (owners and especially the installer).
Keystone Window of Philadelphia (Hatfield, PA) should NOT be one your list of places to get a referral from and certainly do not have the perform an "work" for you.
Avoid Keystone Window of Philadelphia (Hatfield, PA) at all costs. Don't get suckered in by their pricing or "commitment to quality work", shop around and find a reputable and knowledgeable window and door installation company. A quick Google search will help you find a company that actually knows what they are doing.
Reason of review: Poor customer service.