Several years ago I bought both rolling chests,risers,and tool boxes from Costco. They are made of red oak,except for the sides of the rolling chests,which are MDF,veneered. I have had no problem with these chests holding weight.
But,these chests are very different from the chest being shown here. Mine are a lot more like Gerstners. Not quite as nice,but they were 10% of Gerstner price. So,a bargain,I think.