The shoulder pads are wonderful for distributing the weight better on the shoulders and thus increasing the comfort for the wearer.

They are simply velcroed onto the shoulder straps.

You can also use the shoulder pads for other purposes, e.g. to cushion buckles on hip belts of stretchers (regardless of manufacturer) that pinch you.

Details: 
Material: 100% natural cotton
Weave: Cross twill
Colors: Grey
Dimensions: 7.8 inches x 3.9 inches / 20 cm x 10 cm
Washable: Hand wash with liquid mild detergent. Not suitable for the dryer. Do not iron.