Joists are engineered wood joists with wood top and bottom and plywood mesh. It’s made by TrusJoist and 16 inches deep. It is part of the 230 series with reference to the size of the upper chord. Head is 3-1 / 2×16 “tall LVL or plywood. It’s made of two pieces with thickness of 1-3 / 4” LVL material kinda similar to plywood on steroids. DJ stands for double transom What else do you want to know?