A spring bar is a small, cylindrical component used in watchmaking to attach a watch strap or bracelet to the watch case. It consists of a hollow tube with a spring-loaded pin inside, which extends from both ends. The spring bar is designed to fit into the lugs of a watch case, where it is held in place by the tension of the spring. This mechanism allows for easy attachment and removal of watch straps, facilitating quick strap changes without the need for specialized tools.

Spring bars are typically made from stainless steel due to its durability and resistance to corrosion, ensuring the secure attachment of the strap or bracelet. They come in various sizes to accommodate different lug widths and strap thicknesses, making them a versatile component in watch design and maintenance.

The use of spring bars enhances the functionality and versatility of watches, allowing wearers to customize their timepieces with different straps for various occasions. This adaptability is particularly valued in the horology community, where personalization and style are important aspects of watch ownership. Proper maintenance and occasional replacement of spring bars are essential to ensure the safety and longevity of the watch and its strap.