Consisting of 2 layers of microfiber and made to fit with any Regular insert option of the same size. Snap in the Doubler option and snap a Regular insert of your choice on top! Best Bottom Cloth Diaper Doublers are almost identical to the Microfiber Overnight inserts. The only major difference is thickness. Less layers of microfiber result in a thinner insert, a less bulky diaper, and more mobile baby!