Interlocking unit anchors for concrete lining

Claim 1

A METAL ARTICLE, SUBSTANTIALLY L-SHAPED, AND ADAPTED FOR INTERLOCKING WITH A NUMBER OF OTHER LIKE ARTICLES TO PROVIDE ANCHORAGE FOR CONCRETE APPLIED TO A SURFACE, SAID ARTICLE BEING FORMED FROM A METAL STRIP HAVING A TOP EDGE AND A BOTTOM EDGE AND COMPRISING A FIRST LEG; A FIRST HOOK ELEMENT CONNECTED TO SAID FIRST LEG AT THE EXTREMITY THEREOF AND EXTENDING THEREFROM IN THE DIRECTION OF SAID FIRST LEG, SAID HOOK OPENING TOWARD THE TOP EDGE OF SAID ARTICLE; A SECOND LEG AT AN ANGLE TO SAID FIRST LEG, SAID SECOND LEG PROVIDED WITH AN OFFSET ALONG ITS LENGTH; A SECOND HOOK ELEMENT CONNECTED TO SAID SECOND LEG AT THE EXTREMITY THEREOF AND EXTENDING THEREFROM SUBSTANTIALLY PERPENDICULARLY THERETO AND IN THE SAME DIRECTION AS SAID FIRST LEG, SAID SECOND HOOK ELEMENT OPENING TOWARD THE TOP EDGE OF SAID ARTICLE AND THE OPENING THEREIN BEING IN SUBSTANTIAL ALIGNMENT WITH THAT PORTION OF SAID SECOND LEG WHICH IS NOT OFFSET; AT LEAST A PORTION OF SAID SECOND LEG BEING RECESSED ALONG THE BOTTOM EDGE THEREOF SO AS TO RECEIVE A HOOK ELEMENT FROM ANOTHER LIKE ARTICLE AND MAINTAIN SAID OTHER ARTICLE AGAINST SAID SURFACE WHEN ATTACHED THERETO.