A double-ended bolt is a special type of fastener that has external threads on both ends and a smooth shaft (or full threads) in the middle. Its core function is to achieve "disposable connection between two components", and it is particularly suitable for scenarios where one of the connected parts cannot penetrate (such as blind holes), requires frequent disassembly (to avoid damaging the threaded holes), or where space is limited. Its design is centered around "meshing at both ends and transmitting load in the middle", and it is widely used in fields such as machinery, automobiles, chemicals, aerospace, etc.