各种材料及规格的发条的英文

technology for making main and hair ring of various materials and ecificatio

technology for making main and hair spring of various materials and specifications

• 材料:    material
• 及:    reach; come up to
• 规格:    specifications; no ...
• 的:    4次方是 The fourth po ...
• 发条:    spring; remontoir; ...