be provided with a pair of molded in raised stops 64 disposed in substantially diagonal relation to one another on opposite sides of the access opening 62 in the illustrated exemplary construction the raised stops are oriented approximately 180 degrees from one another at positions generally at the intersections between substantially straight lateral sides 66 and curved ends 68 in the illustrated exemplary construction lead in ramps 70 may extent generally along the edges of the lateral sides 66 in this construction the elevation of the lead in ramps 70 progressively increases as they approach the raised stops 64 referring now jointly to fig6 8 it will be understood that during use the lower collar 14 may be inserted in substantially aligned relation into the access opening 62 in the retaining panel 60 until further insertion is blocked by the interference between the retaining panel 60 and the upper collar 12 due to the inability of the upper collar 12 to enter the access opening as will be appreciated once the lower collar 14 has been inserted the retaining panel 60 is disposed in sandwiched relation between the upper collar 12 and the lower collar 14 and the neck 20 is disposed at the interior of the access opening 62 in the initial aligned insertion condition the grommet 10 remains rotatable relative to the retaining panel 60 thus.