Closca Design is a Spanish company producing sustainable everyday products. ‘Thoughtful design’ sums up Closca to a tee. Closca Masks make use of velcro, which closes around the back of the head making them more comfortable. Having washable filters is also an added feature on the Closca Masks. 1 mask set comes with 6 filters that are neatly held in place with a dedicated compartment. These filters can be washed up to 3 times.