Includes a friction block and a friction board (both made of high-quality, smoothly finished wood), three 50-g weights and a 100-g spring scale. The friction block has a hook for a spring scale and 2 compartments for additional weights. Students can vary the weight or area of contact to see their impact on the friction force. Board dimensions, 20 × 2"; block measures 4 × 1 1/2 × 1". Includes instruction manual.