There are two manholes provided on the trailer. One is on the second floor and is approximately 36” in diameter. The second manhole is on the first floor and is offset from the top one and approximately 28” in diameter. If you want to start off even larger, the 4’x4’ hole under the roof prop can be used. The second floor manholes allow for a tripod or a Tower Ladder to be used as a high point. The first floor manhole is more of a challenge with an 8’ ceiling and a smaller opening. You can then lower a rescuer under the trailer into a realistic “confined space”.