Are s3 and s5 straps common?

Not universal. Xiaoxun Watch is a children's smart watch, which is the brand of Xiaomi ecological chain. It is specially designed for children's daily sports. S5 and P5 straps are interchangeable, that is, the dial can be disassembled and interchanged at will. However, the S3 model of Xiaoxun Watch adopts the design of separating the strap from the dial, which is not interoperable with the dial of S5 model. Xiaoxun Watch has completely upgraded the XunOS2.5 sports learning system. In addition to the common step counting function, the newly upgraded sports system also supports outdoor running and skipping.