of the upper sleeve portion 21 because of its relatively small outer diameter the shank portion 35 of the pin 16 passes freely through the upper sleeve portion 21 and the stem portion 25 however upon entering into the latch portion 27 the outer diameter of the shank portion 35 engages and radially expands the bifurcations 28 29 into engagement with an opposite side 50 of the first board 12 opposite to the one side 24 facing the board 13 accordingly the spacer sleeve 15 becomes securely fixed to the first board 12 in addition internal burrs on the ring portion 57 engage the shank portion 35 to retard removal of the pin 16 from the sleeve 15 the second board 13 is mounted next by passing a hole 39 over each head portion 36 until the side 48 facing the board 12 engages the flange portion 37 of the actuator pin 16 during this relative movement between the second board 13 and the body portion 21 the edge 18 engages the cam surface 49 on the third leg 46 forcing the resilient appendage 54 outwardly to permit further movement of the board 13 into engagement with the flange portion 37 after passage of the edge 18 by the third leg 46 the relaxation forces cause the resilient appendage 43 to deflect inwardly into its original position wherein the third leg 46 engages the opposite side 47 of the board 13 thus the second board 13 is fixed securely relative to the first board 12 as the second board 13 is pressed into position under the third legs 46 a spacing is established between the boards 12 13 that is less than the total length of each grounding element 51 the resilient.