The pen is insulated, feeling safe to cleaning your battery operated devices Twist end of the sanding brush pen to reach the desired length of bristles and stiffness as need The scratch brush pen can apply in many applications, the pen brush is good for tight place, electronic applications, rust 3 kind of scratch brush pen in different materials, meet the cleaning and sanding needs of various scenario The fiberglass brushes are soft, good to cleaning your jewelry, watch and coin, Manufacturer: Kelisdi