Removable and fixed prosthesis are fabricated for reasons of appearance, mastication, speech clarity and general well - being. At the same time, they must preserve remaining theeth. Alveolar bone, Ginginal tissue and tooth position by bringing the forces acting on the removavle prosthesis within the limits of tissue tolerance. Satisfying these objectives may reqiure the use of single crowns of fixed partial denture with specific contours and attachments that provide the necessary support and retention for the prosthesis.However, before any detailde discussion can takeplace, it is desirble to divide attachments into groups. Several classifications have been divised, based mainly on the attributes claimed for the devices by the attachment manufactures.Since the function severed by an attachment depend entirely upon the manner in which it is used and function in the mouth are complex and by no means completely understood, the classification of prefabricated attachments used in this title has been based on their shape.