Double Pane Tempered / Safety Glass Low-E Octagon Window 

Constructed of energy efficient polyvinyl-chloride (PVC) which will not Warp, Peel or Corrode. No painting required !

U Rating: 0.265

Visible Light Transmittance (VLT): ~61%

3.2mil Tempered Glass

3/4" Nail / Screw Flange
Maintenance Free
3/4" Insulated Glass

Measures:
Back Part of Window that will fit into your opening will measure 18" x 18"
Your Rough Cut Needs 18-1/8" x 18-1/8"
Over all (end of flange to end of flange)  20" x 20"
Dept of Window 3.5"