The four different attachments adapt to countless applications & are readily interchangeable being clamped by a ball swivel-joint, which permits adjustment to an angular position or true concentricity. working centres & adges can be quickly & accurately located, including confined areas such as slots or shallow holes. with starrett last word test indicators, the user can check run-out or concentricity, establish centre distances & check straightness or alignment of flat surfaces. Centre finder with pointed shank, ball contact, disc contact & offset indicator holder in case.