Whether you're remodeling your home or performing client work in their space, there may come a time when you need to place something on one side of a wall, yet must feed or cut it from the other side of the wall. (Think of wiring that you'd like to precisely line up with an electronic component, or vents for an appliance.) You can try measuring one side of the wall, then walking around to mark the measurement on the other side, but that can be problematic when going from inside to outside, or if there is a level change that alters your reference point (i.e. a room on one side, a staircase on the other).
Here an experienced carpenter shows you the trick he learned from his mentor to transfer a measurement from one side of a wall to the other quickly and flawlessly: