After the folding sheet is buckled once, a reverse buckled sheet is buckled again. The reverse buckled sheet is in close contact with the cassette cover, and convex points are set to buckle with concave holes. The utility model has the advantages that a reverse direction buckle is arranged to prevent the interface of the watch strap from tripping due to accidental pulling, the buckle is stable, and the length of the watch strap can be adjusted in a small amount. The disadvantage is that, except for the same as the above two items, if the other edge of the strap cover is scratched and hung with sharp objects, it is easy to loose the opening and affect the appearance; it is inconvenient to buckle and use.
