11 the opening formed by the circle and square 11 12 for the purposes of the present application will be referred to as a 34 counterbore 34 but it should be understood that this is not intended in the conventional sense of a cylindrical recess for receiving the head of a screw or bolt the counterbore need not extend all the way to the threaded inner bore portion 10 but rather can be separated therefrom after extending for a depth of for example 5 mm by an enlarged cylindrical bore portion 13 this form of blind bore construction it should be recognized will greatly simplify manufacturing since it is much simpler to form bores of circular transverse cross section by drilling milling or the like than it is to form bores or bore portions of non circular cross section and in this manner the only planar portions that need be produced are the relatively small 5 mm deep corner portions 12 additionally the configuration of the lock housing portion 4 and blind bore 9 not only facilitates manufacture thereof but also improves the lock itself in comparison to one which for example utilizes mating rectangular configurations that is this particular configuration is particularly suitable for locks that are utilized in an outdoor environment or other environments wherein the lock will be exposed to grease dirt and the.