I would recommend not using Dart Glass!
1) This window leaks severely, doesn't sit square in the frame, and is improperly sized. (see photos)
Dart Glass plans to just redo the caulk from the outside.
2) A second window, cracked at installation, will eventually be replaced.
3) Of 7 windows, only 6 were measured and installed.
I am a tenant, so don't know Approximate Cost.