Suunto Ath4 Silicone Strap Forest/Copper M

This strap fits: Suunto Spartan Sport Wrist HR & Spartan Sport.

How is the size of the watch measured?
The diameter
The common term is diameter, but since not all watches have circular watch cases, the diameter is actually the width measured from left to right. Note that some manufacturers include the crown (to set the clock) and the buttons when measuring the width, but we try to standardize all the watches by not including the crown as part of the measured width.

Case Thickness
The thickness – or height of the watch in profile – is indicated by measuring the watch from top to bottom as illustrated below. By comparison, a 1-euro coin is 2.33 millimeters thick.
One usually defines the watches with these numbers:
Slim: 4-6 millimeter
Normal: 6-12 millimeter
Big: 12-14 millimeter
Oversize: 14-18 millimeter