| 摘要 |
A security fastener is combined with an anti-rotational member provided with an abutment, such as a knurled face, one or more dogs, or a protuberance, for engaging a surface of a structure to be fastened, to preÂvent unauthorised rotation of the fastener. The anti-rotational member may be a dogged washer defining one or more of the dogs. Alternatively, the anti-rotational member may be a shroud which also defines the abutment in the form of a dog or other protuberance to prevent unauthorised rotation of the encoded security fastener. The shroud may be used in conjunction with a dogged washer and may only partially cover the head of the security fastener. |
