The test tube holders are compatible with all Kuhner universal trays. They are made of stainless steel and the angle of the holder is adjustable. The number of tubes per holder is determined by the size of the tube.
Please note:
For 15ml Falcon, Corning and TPP tubes use holder RGH-16.
For 50ml Falcon, Corning and TPP tubes use the RGH-28.