When skiing, it is probably really necessary, otherwise the lens fogs up quickly (for physical reasons: Warm air absorbs more moisture when it then cools the cold case (the camera's hot) fogging up there). The cushion just take this moisture before it comes to housing. They are reusable and help there already. Only the price I think is totally overpriced (for example, if one views it, for example, silica gel compares with usual drying agents). On warm days (spring / summer / fall) one does not need it!