depth of each slot 24 whereby the latch members can move freely within the slots between the fig1 and fig2 positions the latch members prevent fastener element 18 from pulling out of socket 16 fig1 represents the normal position of fastener element 18 in the event of an impact of a predetermined magnitude on trim panel 10 some of the impact may be absorbed by panel 10 some of the impact however can be transmitted through the panel to fastener element 18 whereby the fastener element is driven deeper into socket 16 as depicted in fig2 as fastener element 18 moves from its normal fig1 position deeper into socket 16 the transverse walls 30 30a hingedly deflect to the folded conditions depicted in fig2 referring to fig4 the hinging motion causes the inner concave surface 31 of the hinge wall to undergo compression the outer convex surface 33 of the hinge wall is in tension the compression tension forces cause the outer face area 35 of the wall to have forcible contact with socket surface 22 the increased frictional contact pressure enhances the energy absorption of the fastener system walls 30 30a are preferably spaced along trunk 28 so that outer edges 27 on one wall are.