Sold in 12" increments.
8mm x 6mm or 4mm x 2.5mm is commonly used on La Spaziale espresso machines.
The 4mm x 2.5mm is most commonly used in La Spaziale Dream and Dream T espresso machines.
The 3mm x 5mm and 4mm x 6mm teflon tubing is commonly used on Quick Mill espresso machines.
TUTE3X5 is also used in the no burn steam arms on the QM machines & some others.