Smaller version of the BestBox-50 holds 0.5 ml tubes. Each cell measures 10 x 10 x 24 mm H. The telescoping lid has a frosted labeling surface, and there are finger grips for easy opening. Measures 4 11/16" L x 2 7/16" W x 1" H with lid in place. Natural polypropylene. (Two BestBox-50 Jr. boxes will fit side by side in freezer racks designed for the BestBox 81-place box or a standard 5 square, 2 H cardboard box.)