Chicago has been plagued with rain and high speed winds for the past couple of days (Typical late fall weather in The Chi). Last year, when this weather was around, I had old, rotted Kolbe\Kolbe casements in my front room with a light weight curtain covering them. The windows were so far gone, I could see the curtain blowing from the air passing right through the windows. So, this past Spring, I had Okna 700 series casements installed by Dave (Window4u) and his crew.
Fast forward to last night. The winds were peaking at around 50mph with driving rain. I watched the curtain during the storm. Didn't move at all. I also ran my hand past the windows. Not a lick of air was getting through.
Okna 1 - High Speed winds 0
I'm very happy with the product Okna makes and with Dave for his recommendation and excellent install. If anyone was in the market for replacement casement windows, I would highly recommend Okna.