Still waiting for my new windows. Like meljabro describes below "are lexan plastic bolted over cutouts. There aren't any frames or anything, just the lexan".
They are thru bolted with barrel nuts likes these:
Beckson Barrel Nut
1. I was going to just use the butyl tape. Do I need to use a 2nd sealant as well?
2. are there better screws than the barrel nuts that I should use? Should I use bolts with nuts and washers instead? There is not a lot of room on the inside for large washers. Too large and the washer would extend into the window cutout area.