Assembly:
Peel back two layers of neoprene from the strap: the entire lower edge can be opened, as it is secured by a Velcro band.
Slide the silicone strap of your mask between the two layers of the neoprene strap. Close the two edges of the neoprene strap, making sure that the two edges of the Velcro match.

Dimensions: 22x9x0,5 cm, approx.
Material: Double-lined neoprene