A threaded fastener for installation in an aperture in a workpiece, the fastener having a rear portion defining an internally threaded aperture and a front portion arranged to engage the rear portion and having a front aperture which is aligned with the threaded aperture when the two portions are fully engaged, both portions having bearing surfaces for bearing on the rear and front of a workpiece respectively and the engagement between the portions being arranged to accurately control the distance between the front and rear bearing faces.