obtain the materials in the quantities shown

screw the U-bracket onto one of the 8" strut channels, using one of the 1/2" hex bolts and the 1/2" strut channel nut

attach the remaining 8" strut channel piece to the U-bracket, using two 1/2" hex bolts and two 1/2" hex nuts

be sure not to center the strut channel you are attaching the the U-bracket, instead make one side of the U-bracket flush with end of the strut channel (as shown)