The Universal Combi Rack is designed to hold a variety of tube sizes.
The rack may be rotated to any of the four positions.

Combinations:
40 place - 12mm tubes (hole dim: 13mm)
8 place - 50ml capacity tubes (hole dim: 30mm)
24 place - 15ml capacity tubes (hole dim: 17mm)
20 place - 20mm tubes (hole dim: 21mm)

Instruction Sheet included.