numerical references used in the description with reference to the earlier embodiment are employed for the same or similar integers hereinafter and it is believed that only differences between the two need to be included in this embodiment the second bracing member in the form of a buttress or stiffening element 60 is provided to improve structural strength of the support arm 42 and the retainer arm 44 the buttress element extends from the second surface 22 b and bridging the arms 42 and 44 accordingly deflection movement of the two arms 42 and 44 is substantially restricted and thereby providing improved retention of the fence 12 each of the extensions 34 a and 34 b has an area 62 with a reduced thickness the first bracing means in the form of a bracing element 64 is interconnected between the first surface 22 a and each of the extensions 34 a and 34 b as such the structural strength or stiffness of the extensions 34 a and 34 b is also substantially improved even with the reduced thickness areas 62 the cord like extension 32 in this embodiment has enlarged sections at its ends which are formed with the body 20 and the pin 28 respectively while not shown it.