StonyLab Borosilicate Glass Round Bottom Test Tubes, 30mm OD X 165mm Length (Pack of 15) : Amazon.ca: Industrial & Scientific
Amazon.com : Starboosa Telescope T2-Extension Tube Kit for Cameras and eyepieces - Length 3mm 5mm 7mm 15mm 20mm 30mm - M42x0.75 on Both Sides : Electronics
Amazon.com: uxcell Clear Rigid Storage Tubing with White Lids 30mm(1.18'') ID x 32mm(1.26'') OD x 0.82Ft Length Round Plastic Polycarbonate Tube : Industrial & Scientific