Falcon Tube Rack (10mL), with 1.8mm hole diameter
There are three versions of the rack: A1 for 60 tubes, B2 for 50 tubes and C3 for 18 tubes

The set consists of 5 parts: 2 side supports + 2 rack top (1.8mm) + 1 base with smaller holes (1.5mm)
The side support is universal to all versions of the racks, the base of the rack has a diameter slightly smaller than 1.8mm to ensure that the tubes do not fall.