1、Made of acid-resistant stainless steel, this test tube rack is acid and corrosion resistant and durable 2、Each tube rack has 40 holes with different diameters to meet your needs 3、Professional manufacturing, exquisite workmanship, beautiful and practical, long-term use 4、Ability to suspend test tubes or colorimetric tubes during chemical experiments and drying tubes 5、Can also be used for non-traditional purposes, such as pen holders, brush holders, etc Features: Made of acid-resistant stainless steel, this test tube rack is acid and corrosion resistant and durable. Each tube rack has 40 holes with different diameters to meet your needs. Professional manufacturing, exquisite workmanship, beautiful and practical, long-term use. Ability to suspend test tubes or colorimetric tubes during chemical experiments and drying tubes. Can also be used for non-traditional purposes, such as pen holders, brush holders, etc. Specification: Condition: 100% Brand New Material: Stainless Steel Type: 15.5mm, 18.5mm, 20.5mm (Optional) Instructions: 15.5mm for fixing standard test tubes from 15mm to 16mm 18.5 mm for fixing test tubes from 17mm to 18mm 20.5 mm for fixing test tubes from 20mm to 21mm Weight: 15.5mm: Approx. 401g / 14.1oz 18.5mm: Approx. 488g / 17.2oz 20.5mm: Approx. 520g / 18.3oz Diameter: 15.5mm: Approx. 15.5mm / 0.6in 18.5mm: Approx. 18.5mm / 0.7in 20.5mm: Approx. 20.5mm / 0.8in Package List: 1 x Test Tube Holder