That right there is a riser, a riser I built as part of finishing my basement. It is in my movie room so that those banished to the back row of seats can see over the heads of their betters, namely those important enough to be allowed to sit in the front row. It is roughly eight feet by eleven feet, a super fortified combination of plywood, two-by-sixes, two-by-fours, sweat, blood and gumption. It is very big. It is very heavy. It is not fun to move, something I can now attest to personally.