A connection assembly adapted for receipt of a male connection member at the interior of a grommet for operative attachment of a retaining panel to a substructure, the connection assembly comprising: the variable profile grommet of hollow unitary construction formed from elastomeric material comprising a first collar having a first effective diameter, a second collar disposed in spaced-apart relation from the first collar, the second collar being of substantially non-circular geometry defining a second effective diameter, the grommet further comprising a neck extending between the first collar and the second collar, and wherein an axial bore extends entirely through the grommet; a sleeve insert comprising a hollow stem extending from a point of insertion on one side of the grommet into the axial bore so as to at least partially line the axial bore, the stem comprising a proximal end and a distal end, the sleeve insert further comprising an annular flange extending radially outwardly away from the proximal end of the stem, the annular flange having a diameter greater than the axial bore at the point of insertion; and the retaining panel including a substantially non-circular access opening adapted to receive the second collar in pass-through relation when the second collar is aligned with the access opening, the access opening being further adapted to block the first collar against pass-through insertion, and wherein upon rotation of the grommet following insertion of the second collar, the grommet is blocked against withdrawal through the access opening and the retaining panel is held between the first collar and the second collar with the second collar disposed in partial surrounding relation to the access opening, characterized in that the second collar has a lobe-shaped perimeter with a pair of opposing, substantially straight lateral sides, and that the retaining panel includes a pair of raised stops projecting away from the underside of the retaining panel at positions outboard from the access opening in adjacent relation to molded integral lead-in ramps, wherein the raised stops project away from the underside of the retaining panel to a distance greater than the height of the lead-in ramps and herein upon rotation of the grommet following insertion of the second collar, the second collar travels up the lead in ramps until at least one of the lateral sides contacts at least one of the raised stops to define a locked condition with portions of the access opening adjacent to the lateral sides remaining uncovered by the second collar. the variable profile grommet of hollow unitary construction formed from elastomeric material comprising a first collar having a first effective diameter, a second collar disposed in spaced-apart relation from the first collar, the second collar being of substantially non-circular geometry defining a second effective diameter, the grommet further comprising a neck extending between the first collar and the second collar, and wherein an axial bore extends entirely through the grommet; a sleeve insert comprising a hollow stem extending from a point of insertion on one side of the grommet into the axial bore so as to at least partially line the axial bore, the stem comprising a proximal end and a distal end, the sleeve insert further comprising an annular flange extending radially outwardly away from the proximal end of the stem, the annular flange having a diameter greater than the axial bore at the point of insertion; and the retaining panel including a substantially non-circular access opening adapted to receive the second collar in pass-through relation when the second collar is aligned with the access opening, the access opening being further adapted to block the first collar against pass-through insertion, and wherein upon rotation of the grommet following insertion of the second collar, the grommet is blocked against withdrawal through the access opening and the retaining panel is held between the first collar and the second collar with the second collar disposed in partial surrounding relation to the access opening, characterized in that the second collar has a lobe-shaped perimeter with a pair of opposing, substantially straight lateral sides, and that the retaining panel includes a pair of raised stops projecting away from the underside of the retaining panel at positions outboard from the access opening in adjacent relation to molded integral lead-in ramps, wherein the raised stops project away from the underside of the retaining panel to a distance greater than the height of the lead-in ramps and herein upon rotation of the grommet following insertion of the second collar, the second collar travels up the lead in ramps until at least one of the lateral sides contacts at least one of the raised stops to define a locked condition with portions of the access opening adjacent to the lateral sides remaining uncovered by the second collar.