When dealing with glass lights in doors, there are three (3) critical dimensions which must be coordinated:

Exposed Glass Size (EGS) - the horizontal and/or vertical dimensional size of the vision area of a glass light in a door (the actual size of the window you look thru). Exposed glass size may also be referred to as visible glass size.

1. This is the window dimension most commonly specified and the basis for developing the Door Cutout Size and the Glass Cutting Size.

Glass Cutting Size (GCS) - the net horizontal and/or vertical dimensional size of the glass being fit into the door window preparation.

1. Glass cutting size is the critical dimension which a distributor needs to order the glass or to cut the glass in their shop.
2. For Steelcraft trim: GCS = EGS + 1 1/4"  Ex: N5 (5" x 20") = 6 1/4" x 21 1/4" glass cutting size
3. For non-Steelcraft trim: specifying the glass cutting size for non-Steelcraft glass systems is the responsibility of the distributor.

Door Cutout Size (DCS) - the horizontal and/or vertical dimensional size of the of the cutout in the door required to accept the required glass trim.

1. For Steelcraft trim: GCS = EGS + 1 19/32" 
2. For non-Steelcraft trim: The distributor must supply this dimension.