The dimensions of the Holy Ark in the Tabernacle are different than the other vessels. None of its measurements are whole numbers. We find that it was to be two and a half cubits long, one and a half cubits wide and one and a half cubits high. (Exodus 25:10).
The Ark housed the Tablets of the Ten Commandments as well as the Torah. The Mei HaShiloach teaches that we are only able to receive Torah if we feel incomplete and lacking. The person who lacks this humility and feels totally complete as they are cannot be a fit vessel to absorb Torah.