There are other tube racks that claim to be multi-purpose, but in order to accomodate tubes of different sizes, you must flip the rack to a different side.
The Adapt-a-rack™ is able to accommodate 12 mm–30 mm (5 mL–50 mL) tubes at once in any of the four slots, and hold them in a firm upright position
Racks are interlockable to form a larger collection of tubes.
-- Made from POM
-- Racks can be linked together for additional holding capacity
-- Open sides allow for label viewing
-- Flat base to hold tubes upright
-- Linked racks should be supported underneath when carrying
-- Available in solid or a combination of colors for easy coding identification