Apple Watch Strap

Hello,

WHAT IS COVERED BY THIS WARRANTY?

• Apple Inc. of One Apple Park Way, Cupertino, California, U.S.A. 95014 (“Apple”) warrants the Apple-branded hardware product and Apple-branded accessories contained in the original packaging (“Apple Product”) against defects in materials and workmanship when used normally in accordance with Apple's published guidelines for a period of ONE (1) YEAR from the date of original retail purchase by the end-user purchaser ("Warranty Period"). Apple’s published guidelines include but are not limited to information contained in technical specifications, user manuals and service communications. 

One year.

Or the user manual.

It means something like this (Change your Apple Watch band - Apple Support).