20 types and 200 pieces: 20 different sizes and dimensions of springs, 124 pieces of tension springs and 76 pieces of compression springs, totaling 200 pieces. Fulfills a wide variety of needs. STRONG AND DURABLE: Flexible springs are made of #75 zinc-plated spring steel to provide extra durability for proper tension. Smooth and knock-free for stability and durability. VERSATILE USE: These compression springs are widely used in construction, automobiles, stores, airplanes, machinery, appliances, furniture, etc. for splicing between sheets and holding objects in place. EASY STORAGE: Comes with durable plastic storage box with individual slots to separate each product size independently, compare with the size chart on the lid for easy identification, use and carrying. Dimensions: Extended: 5.16x20.6 6.35x22.2 5.55x25.4 7.93x28.5 7.93x31.7 8.73x36.5 7.14x38.1 8.73x46.8 7.14x50.8 7.93x44.4 4.76x44.4 3.96x79 .3 mm, Compressed: 6.35x10.3 7.14x12.7 5.55x17.4 7.14x19.05 9.52x15.8 9.52x19.05 9.12x34.9 5.55x38.1 mm.