Abstract: Improvements in a forklift adapter to offer a way of double-stacking pallets by a single forklift operator, using an existing forklift equipped with single-double forks using existing forklift controls, which is both unique and superior to using two or three people to perform the same task manually. Double-stacking pallets are accomplished by placing a sheet of material on top of a first loaded pallet of material. The blades of the forklifts slide into rectangular tubes on the forklift adapter. Sheet material is gripped by a plurality of pins on the forklift adapter where the depth of the pins is adjustable. The forklift adapter utilizes a spring that provides the gripping force. Using a spring to provide to grip provides consistent force. The spring material, coils, spring force and spring length all have factors that can change the gripping force.