A deployment buckle is a folding clasp mechanism on the watch strap that lets it fold neatly into itself, making it comfortable to put on and take off the watch without exerting much stress on the strap. It consists of a folding metal clasp that "deploys" when opened and snaps shut in closing to hold securely the watch against the wrist, which this strap-in design calls home. It is a kind of buckle that would give more comfort and longevity since there would be less friction on the strap, thus preventing it from being rubbed or pulled through a common buckle.
Deployant buckles are very well-known in leather and metal straps; they have more convenience and a refined look for an individual's wrist.
