he made it himself. Looks like a perferreted type but has folds that create rasied ribs in it that run horizonatally. The ribs would be about 1 inch proud of the face and about an inch wide (vertical face) the folds were not 90° maybe 75°-80°...having the folds actually means there is more surface area of sheet = more holes = more air flow than if it was just flat perrferated sheet. I agree with what Tombie is saying, But IMO this makes a very strong and functional grill....and Im the first one to be concerned about heat and airflow.

