The length of the strap can be adjusted by the wearer without the need for a watchmaker. A flat object such as a flat-headed screwdriver is usually used to open the clasp and adjust the strap.
You don't see the size? What do you think the number 27.80mm in the product name stands for? Have you looked at anything at all? Among other things, the following information can be found in the specifications:
Target group ladies, men
Product dimensions
Case diameter 27.80 mm
Case thickness 8.10 mm
Weight 44 g