Silicone tubing
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Normal wall. Translucent.
A N3, 3mm bore, 0.75mm wall, 1 meter length
B N5, 5mm bore, 1.5mm wall, 1 meter length
C N8, 8mm bore, 2.0mm wall, 1 meter length
N8 tubing fits most bunsen burners and gas taps.