I am selling these because I only used a few of them and no longer need them. 1. Excellent characteristics: durable and long-lasting with solid spring steel, and wear-resistant. Suitable for maintenance in shops, homes, etc. 2. Set of 200 pieces: Includes compression springs and extension springs, 20 types in total, 200 pieces. Case size: approx. 20.7 x 11 x 2.8cm. 3. Extension springs (12 types, 124pcs): 5*20.5mm (10pcs), 5.5*25.5mm (10pcs), 6.5*22mm (10pcs), 8.5*47mm (12pcs), 7*51mm (12pcs), 7*38mm (10pcs), 8.5*36.5mm (10pcs), 8*28.5mm (8pcs), 8*31.5mm (10pcs), 8*44.5mm (12pcs), 4*79.5mm (12pcs), 4.5*44.5mm (8 pcs). 4. Compression springs (8 types, 76pcs): 7*12.5mm (10pcs), 6.5*10mm (10pcs), 7*19mm (10pcs), 5.5*38mm (10pcs), 9.5*16mm (6pcs), 9.5*19mm (12pcs), 9*35mm (8pcs), 5.5*17mm (10pcs)