Heathrow Scientific HS29022G 4 Way Tube Rack, Polypropylene, Assorted Colors, Blue, Green, Pink, Yellow, Orange (Pack of 5) Create as large a rack as you need by linking together multiple racks Heavy-duty polypropylene racks feature a unique system of tabs and slots, which facilitate easy connection and sturdy fit Autoclavable Each rack can hold different sized tubes on each side, Side 1 ( 4 - 50mL tubes), Side 2 (12 - 15mL conical tubes), Side 3 (32 - 1.5/2.0mL tubes), Side 4 (32 - 0.5mL microtubes) Conveniently connect end to end or side to side