will chip or break away or in some cases not even exist because of an air pocket underneath the contact point thus creating the very bending moment m that should be nearly eliminated otherwise in the preferred mode of the invention the extensions are placed so as to enhance the possibility that there is full concrete flow around the contact points 47 and 52 in fig5 c this minimum area of coverage is shown as the dashed circle 60 and 62 in fig5 c although as will be seen in practice the concrete will likely fill in the entire hole represented by the dashed perimeter 46 the invention accomplishes this in the preferred mode by providing that the contact points of the extensions are essentially in a linear form as represented by the vertical dashed line 64 in fig5 c placing them other than inline for example near the perimeter of the hole 46 enhances the possibility that there will not be full flow of concrete around the contact point the bends in the extensions not only provide means for u201c retaining u201d the extensions around the vertical rebar in the wall but also require that the hole 46 be cut large enough to insert the device through the styrofoam form in other words as previously indicated the contractor utilizing the device has no choice but to cut the holes large enough and by so doing helps assure full flow of the concrete around the contact points in another mode of the invention shown in fig6 and 7 the rigid.