Uniform population density field experimentation can now be done economically and accurately using two 20-m calibrated transect lines and quadrat that complete this classic sampling device. Whether sampling periwinkles in the meadow or pennies on a tabletop, the quadrat can be easily assembled into one square that is 1 m on each side, or 2 squares that are each 0.5 m on each side. This versatile tool has an almost limitless application in all field studies.