Abstract: A bowstring mounted peep sight is disclosed having a peep housing that is frictionally located between displaced bowstring filaments. The peep housing defines a peep hole and a transverse oriented receiving slot. Insertable aperture reducing discs are slidably inserted into the receiving slot to incrementally decrease the relative aperture of the peep hole. To prevent the inserts from being inadvertently dislodged from the receiving slot during use of the invention, one of the displaced bowstring elements is positioned so as to prevent the disc from sliding outwardly therefrom. Because of the design of the peep housing, lightweight materials can be utilized. Frusto conical recesses on both planar surfaces of the peep housing reduce incidental glare thereby increasing the clarity of the observed target.