An attachment mountable to an electric toothbrush handle having a drive shaft comprises a neck member having an elongated body with a principal axis and a cavity; a slide member with an engagement surface; a guide sleeve member having a cavity, a first outer surface with an engagement opening, and a transition surface; and a collar member. The guide sleeve member, with slide member inserted within the engagement opening, is inserted within the neck member cavity. Insertion of the drive shaft into the collar member and guide sleeve member from a first radial position along an axis offset and parallel to the principal axis to a second radial position in-line with the principal axis, via the transition surface, results in the drive shaft being held in frictional contact with the engagement surface of the slide member to enable transfer of force/motion from the drive shaft to the neck member.