We put a Neutradol Gel in our trailer tent before winter storage last year and was really surprised how fresh and nice it smelt when getting it out on Monday for this years use. The gel, in its little jar, was tucked down the side of the bedding and there was no musty/damp smell at all, I think it worked so well because the air space was small but might equally work with tents etc I had a job to find them but bought from amazon in the end as couldn't find the gels in the shops.There was about 1/2 of the gel left and that was after a few months so well worth the couple of pounds in cost.