Yea you definately need a hygrometer, but the packs help keep it at that level so you dont fall below, cause once below a certain humidity curing is done right? you wont be able to cure anymore and if not fully cured yourfucked and bud will taste and smell like hay ive heard, just use em as a extra safeguard, might even try em for my bud right now so it doesnt dry out so much lol, keep it perfect and "always" curing, im kinda sold on em, shoulda mentioned the hygrometer first cause that is a must have tool