Features Ability to hang test tubes or colorimetric tubes during chemical experiments and drying tubes. The test tube rack is made of acid-resistant stainless steel, which is resistant to acid corrosion and durable. Each tube holder has 40 holes of different diameters to suit your needs. Professional manufacturing, exquisite workmanship, beautiful and practical, durable. Can also be used for non-traditional uses such as pen holders, pen holders, etc. Features: -Ability to hang test tubes or colorimetric tubes during chemical experiments and drying tubes. -The test tube rack is made of acid-resistant stainless steel, which is resistant to acid corrosion and durable. -Each tube holder has 40 holes of different diameters to suit your needs. -Professional manufacturing, exquisite workmanship, beautiful and practical, durable. -Can also be used for non-traditional uses such as pen holders, pen 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 Package List