this is the variation on the counter sunk screw head, though the beneath area of the head is curved, just here like a bugle. This minimizes damage to plasterboard reducing tearing of the paper, so is often observed on drywall screws Designed so the screw sits flush Using the surface area remaining fixed, so that The top will not likely capture. Th

To paraphrase, 3 Robertson squares are superimposed in a successive thirty° rotation. the look is comparable to that with the double-square, in equally cases The concept staying that it resembles a sq. (Robertson) but may be engaged at more frequent angles by the driving force little bit. These screws may be driven with common Robertson bits. Pan