The local discount window store is selling an American Weather Seal T10 triple glass low E Krypton gas window claiming .20 U values and 9 R values. Approximate Cost $230 per unit.

Most windows I've seen are double glass and .30 U value is the best they offer with low E coating and gas fill. Makes me think the AWS T10 window is a good deal if it lives up to the performance rating and is good quality - but how can I tell if it is a good quality window.

Does anyone have experience with American Weather Seal? How has it held up for you?

I looking for customer reviews of AWS T10 windows that these are replacement vinyl Slider windows I am looking at. Additionally, I wonder if the increased weight of triple glass could increase friction and make it difficult to open these windows or shorten the track life on a slider?