Horizontal grooves present on the underside of the strap for ventilation purposes. These grooves are made without any complex patterns, and are sufficiently wide, to allow for easy cleaning to any dirt that may build up over time.

Grooves on Underside for Ventilation
Horizontal grooves present on the underside of the strap for ventilation purposes. These grooves are made without any complex patterns, and are sufficiently wide, to allow for easy cleaning to any dirt that may build up over time.