Aluminum extrusion is to put aluminum into a designed mold, after pushing ,aluminum products with the same cross-sectional shape.
A or b means the widest and the highest distance of an extrusion profile.
If the c^2 >16, we can say it's a small-size product.
If the 16>c^2 >49, we can say it's a medium-size product.
If the 49>c^2, we can say it's a big-size product.
For the thickness, thicker is better.
For the hollow parts, less is better.
For the overall situation, the solid profile is better than hollows.
If you insist a big size profile, and also request for thin thickness, you may get a higher price over than your imagination.
Shape(ex. round tube or another)
A: T5 or T6 means heat-treatment level, which related to the hardness.
For the same product, T6 is better than T5. For most of products, T5 is enough, and T6 is better. For hollow products, it would have risk of out-of-shape when you insist T6.
aluminum 6063 or 6061 means the name of aluminum alloy. For the same product, aluminum 6061 is stronger than 6063. For most of products, 6063 is enough, and 6061 is better.
For all products, it would have risk of worse surface when you insist 6061. If you insist to use 6061, and also request for surface beauty, you may get a higher price.