These brackets are designed to attach sections of EMT (electrical conduit) together for an outdoor project.

The OnShape source at https://cad.onshape.com/documents/b4cd7fb6f6077e7dd4747248/w/e2100433a549bb989e2366af/e/c2376d94d6c831a284f9db71?configuration=List_TryvEiRG98E1y1%3D_3_4__EMT&renderMode=0&uiState=670947a3090bce7f5a3f0387 has several different part variations, and all of the sizes can be changed with variables. 

These are not intended to be used to carry any significant load. 

There are holes for an M6 nut and bolt, as well as holes for a screw to be driven into the conduit.