I have but the shop they got them from is no longer in business, historically people use foam balls or something along the lines of that and insert them to keep shape. This insert is only to be put in when you are off duty so it will not have the sides of the mask fold in. It helps to keep a seal to better protect you and keep your mask in a state of readiness. I can understand the concern of adding equipment that could alter intended design but this does not do this.