I installed them and everything looked fine. We drove to our warehouse and I thought the matrix was sunburned (first time and it took 24 hours to install). Then I couldn't see the bubble. The temperature was 91 F. The glass end of the tube broke off and the tube was completely drained. I bought several standard Camco 25523 spirit levels and placed them in various locations. None of them broke, they remain green and relatively accurate. Level with a building level, then set the levels.