Perforated Bricks

I was really excited to find these brick on the clearance shelf at the hardware store. I wanted to build a retaining wall in my backyard, and the brick seemed like a good way to go. However, I was a little dismayed when I tried to fit the bricks together. The bricks were just a little too large for my need, and the only way I could get them to fit together was to leave a gap in the middle. That gap wasnt really what I wanted, so I was stuck using some old bricks I found in my garage to fill the gaps in the new bricks.