STEP 1. Locate the arm in the kit and place on top of new mailbox. Be sure to keep arm towards back of mailbox so it will not interfere with post. Next place the first u bracket between guides and place back bracket at least 3 inches away from drilled holes at end of arm. Mark all four holes in brackets so you know where to drill to install bolts.
Step 2. Connect the arm to post top. Arm will slide inside post top. Align predrilled holes and secure with bolt provided. Please note the bolt must be inserted from bottom and the nut attached on top for proper installation.
Step 3. Drill holes in mailbox using 1/4" or 9/32 drill bit. Apply a sealant around each hole (I use GOOP). Bolt is installed by placing inside mailbox with a washer attached and secured by placing washer in sealant and securing bolt with nuts supplied. Tighten nuts and allow for sealant to set up. Then set arm in place and install the u brackets and secure with lock nut. Be sure to keep from over tightening because it can break the new seal you created earlier.
Step 4. Concrete Base. Find a box that is about 12" square and line the box with a trash bag. (NOTE the box can be whatever size you like. I recommend 12 so the the base will be at least 6 inches thick. A USPS large flat rate is a good size.). Tape off the tops of both 3/4"pieces of PVC provided in the kit. Tape off the 1 1/2" piece end that is not angle cut. Next tape the pieces to the bottom. Pieces may not stand perfectly but this is not an issue. Once concrete is added set up small pvc straight up and 1 1/2 stand at the angle so that bottom is angled properly. I recommend using 50LB bag of concrete and don't worry if you have some left. You can use the 2 small pieces to fill all space by moving them in small circles. Once the concrete begins to cure be sure to rotate the small pieces because it is necessary to remove these pieces. I typically allow a couple of hours, depending on how wet the concrete is, and then turn the small pvc pieces. When concrete appears to be hardening remove both small pieces of pvc. Larger piece remains in concrete permanently. After about 8 hours remove box and bag and allow to cure.