We include an ADJUSTfit insert with every cocksheath - to adjust the inside-shaft length for the best fit for you. ADJUSTfit 3-pack is three more inserts for more exact fit choicesany size guy can feel our sheaths custom fit their sizeadd as many as you want making the sheath feel like it is part of you, feel firm from the base of your shaft to the tip of the sheath.The clear rubbery inserts disappear inside the sheath for a discrete lookthey keep the cocksheath firm even when you arent as firm so you can keep playing hard. Made of clear, discrete Flextpr, they disappear and feel just like your shaft. Each insert shortens the inside shaft about 7/8. Shaped to snugly fit and form together.