Parallelogram of forces apparatus is used to study the relationship between forces in a visually and kinesthetically effective manner. Includes board, 2 pulleys on clamps, iron nickel plated hangers, and slotted weights. Slotted weights weigh 50g each (12 total) - Board measures 26" x 20" x 0.5". Can be mounted onto a wall for easy viewing.Designed for use in professional laboratories, but is an ideal choice for science classrooms and household use.